strict decoding of return values using generics

17 files changed, 815 insertions, 332 deletions

diff --git a/packages/abi-gen-templates/partials/callAsync.handlebars b/packages/abi-gen-templates/partials/callAsync.handlebars
index 37b50307c..ab9f2c21c 100644
--- a/packages/abi-gen-templates/partials/callAsync.handlebars
+++ b/packages/abi-gen-templates/partials/callAsync.handlebars
@@ -16,6 +16,8 @@ async callAsync(
     const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
     BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
     const abiEncoder = self._lookupAbiEncoder('{{this.functionSignature}}');
-    const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-    return resultArray{{#singleReturnValue}}[0]{{/singleReturnValue}};
+    // tslint:disable boolean-naming
+    const result = abiEncoder.strictDecodeReturnValue<{{> return_type outputs=outputs}}>(rawCallResult);
+    // tslint:enable boolean-naming
+    return result;
 },
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/asset_proxy_owner.ts b/packages/abi-gen-wrappers/src/generated-wrappers/asset_proxy_owner.ts
index 05ce2ece8..cc42e7fb5 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/asset_proxy_owner.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/asset_proxy_owner.ts
@@ -118,8 +118,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('owners(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public removeOwner = {
@@ -191,8 +194,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('removeOwner(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public revokeConfirmation = {
@@ -264,8 +270,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('revokeConfirmation(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public isOwner = {
@@ -289,8 +298,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('isOwner(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public confirmations = {
@@ -316,8 +328,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('confirmations(uint256,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public executeRemoveAuthorizedAddressAtIndex = {
@@ -389,8 +404,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('executeRemoveAuthorizedAddressAtIndex(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public secondsTimeLocked = {
@@ -412,8 +430,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('secondsTimeLocked()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getTransactionCount = {
@@ -439,8 +460,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getTransactionCount(bool,bool)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public registerAssetProxy = {
@@ -521,8 +545,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('registerAssetProxy(address,bool)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public addOwner = {
@@ -594,8 +621,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('addOwner(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public isConfirmed = {
@@ -619,8 +649,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('isConfirmed(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public changeTimeLock = {
@@ -692,8 +725,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('changeTimeLock(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public isAssetProxyRegistered = {
@@ -717,8 +753,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('isAssetProxyRegistered(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getConfirmationCount = {
@@ -742,8 +781,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getConfirmationCount(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transactions = {
@@ -767,8 +809,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transactions(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<[string, BigNumber, string, boolean]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getOwners = {
@@ -790,8 +835,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getOwners()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string[]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getTransactionIds = {
@@ -821,8 +869,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getTransactionIds(uint256,uint256,bool,bool)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber[]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getConfirmations = {
@@ -846,8 +897,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getConfirmations(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string[]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transactionCount = {
@@ -869,8 +923,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transactionCount()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public changeRequirement = {
@@ -942,8 +999,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('changeRequirement(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public confirmTransaction = {
@@ -1015,8 +1075,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('confirmTransaction(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public submitTransaction = {
@@ -1106,8 +1169,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('submitTransaction(address,uint256,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public confirmationTimes = {
@@ -1131,8 +1197,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('confirmationTimes(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public MAX_OWNER_COUNT = {
@@ -1154,8 +1223,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('MAX_OWNER_COUNT()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public required = {
@@ -1177,8 +1249,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('required()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public replaceOwner = {
@@ -1259,8 +1334,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('replaceOwner(address,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public executeTransaction = {
@@ -1332,8 +1410,11 @@ export class AssetProxyOwnerContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('executeTransaction(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/dummy_erc20_token.ts b/packages/abi-gen-wrappers/src/generated-wrappers/dummy_erc20_token.ts
index 97aa8c608..cab09c4d2 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/dummy_erc20_token.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/dummy_erc20_token.ts
@@ -55,8 +55,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('name()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public approve = {
@@ -137,8 +140,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('approve(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public totalSupply = {
@@ -160,8 +166,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('totalSupply()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferFrom = {
@@ -251,8 +260,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferFrom(address,address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public decimals = {
@@ -274,8 +286,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('decimals()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public balanceOf = {
@@ -299,8 +314,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('balanceOf(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public owner = {
@@ -322,8 +340,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('owner()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public symbol = {
@@ -345,8 +366,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('symbol()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public mint = {
@@ -418,8 +442,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('mint(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transfer = {
@@ -500,8 +527,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transfer(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public allowance = {
@@ -527,8 +557,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('allowance(address,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public setBalance = {
@@ -609,8 +642,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('setBalance(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferOwnership = {
@@ -682,8 +718,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferOwnership(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public MAX_MINT_AMOUNT = {
@@ -705,8 +744,11 @@ export class DummyERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('MAX_MINT_AMOUNT()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/dummy_erc721_token.ts b/packages/abi-gen-wrappers/src/generated-wrappers/dummy_erc721_token.ts
index cfef3ca47..9cb54442b 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/dummy_erc721_token.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/dummy_erc721_token.ts
@@ -63,8 +63,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('name()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getApproved = {
@@ -88,8 +91,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getApproved(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public approve = {
@@ -170,8 +176,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('approve(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferFrom = {
@@ -261,8 +270,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferFrom(address,address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public mint = {
@@ -343,8 +355,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('mint(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public safeTransferFrom1 = {
@@ -434,8 +449,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('safeTransferFrom(address,address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public ownerOf = {
@@ -459,8 +477,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('ownerOf(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public balanceOf = {
@@ -484,8 +505,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('balanceOf(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public owner = {
@@ -507,8 +531,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('owner()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public symbol = {
@@ -530,8 +557,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('symbol()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public burn = {
@@ -612,8 +642,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('burn(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public setApprovalForAll = {
@@ -694,8 +727,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('setApprovalForAll(address,bool)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public safeTransferFrom2 = {
@@ -794,8 +830,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('safeTransferFrom(address,address,uint256,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public isApprovedForAll = {
@@ -821,8 +860,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('isApprovedForAll(address,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferOwnership = {
@@ -894,8 +936,11 @@ export class DummyERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferOwnership(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/dutch_auction.ts b/packages/abi-gen-wrappers/src/generated-wrappers/dutch_auction.ts
index 97340a372..9be95af65 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/dutch_auction.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/dutch_auction.ts
@@ -84,8 +84,11 @@ export class DutchAuctionContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getAuctionDetails((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes))');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{beginTimeSeconds: BigNumber;endTimeSeconds: BigNumber;beginAmount: BigNumber;endAmount: BigNumber;currentAmount: BigNumber;currentTimeSeconds: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public matchOrders = {
@@ -184,8 +187,11 @@ export class DutchAuctionContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('matchOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),(address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),bytes,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{left: {makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber};right: {makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber};leftMakerAssetSpreadAmount: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/erc20_proxy.ts b/packages/abi-gen-wrappers/src/generated-wrappers/erc20_proxy.ts
index 57ce08c10..1d53df6b8 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/erc20_proxy.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/erc20_proxy.ts
@@ -103,8 +103,11 @@ export class ERC20ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('addAuthorizedAddress(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public authorities = {
@@ -128,8 +131,11 @@ export class ERC20ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('authorities(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public removeAuthorizedAddress = {
@@ -201,8 +207,11 @@ export class ERC20ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('removeAuthorizedAddress(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public owner = {
@@ -224,8 +233,11 @@ export class ERC20ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('owner()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public removeAuthorizedAddressAtIndex = {
@@ -306,8 +318,11 @@ export class ERC20ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('removeAuthorizedAddressAtIndex(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getProxyId = {
@@ -329,8 +344,11 @@ export class ERC20ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getProxyId()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public authorized = {
@@ -354,8 +372,11 @@ export class ERC20ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('authorized(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getAuthorizedAddresses = {
@@ -377,8 +398,11 @@ export class ERC20ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getAuthorizedAddresses()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string[]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferOwnership = {
@@ -450,8 +474,11 @@ export class ERC20ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferOwnership(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/erc20_token.ts b/packages/abi-gen-wrappers/src/generated-wrappers/erc20_token.ts
index b49e73c87..5070111e1 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/erc20_token.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/erc20_token.ts
@@ -114,8 +114,11 @@ export class ERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('approve(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public totalSupply = {
@@ -137,8 +140,11 @@ export class ERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('totalSupply()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferFrom = {
@@ -228,8 +234,11 @@ export class ERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferFrom(address,address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public balanceOf = {
@@ -253,8 +262,11 @@ export class ERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('balanceOf(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transfer = {
@@ -335,8 +347,11 @@ export class ERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transfer(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public allowance = {
@@ -362,8 +377,11 @@ export class ERC20TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('allowance(address,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/erc721_proxy.ts b/packages/abi-gen-wrappers/src/generated-wrappers/erc721_proxy.ts
index 5b1eba2af..5a9fcc7d1 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/erc721_proxy.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/erc721_proxy.ts
@@ -103,8 +103,11 @@ export class ERC721ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('addAuthorizedAddress(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public authorities = {
@@ -128,8 +131,11 @@ export class ERC721ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('authorities(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public removeAuthorizedAddress = {
@@ -201,8 +207,11 @@ export class ERC721ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('removeAuthorizedAddress(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public owner = {
@@ -224,8 +233,11 @@ export class ERC721ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('owner()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public removeAuthorizedAddressAtIndex = {
@@ -306,8 +318,11 @@ export class ERC721ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('removeAuthorizedAddressAtIndex(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getProxyId = {
@@ -329,8 +344,11 @@ export class ERC721ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getProxyId()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public authorized = {
@@ -354,8 +372,11 @@ export class ERC721ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('authorized(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getAuthorizedAddresses = {
@@ -377,8 +398,11 @@ export class ERC721ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getAuthorizedAddresses()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string[]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferOwnership = {
@@ -450,8 +474,11 @@ export class ERC721ProxyContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferOwnership(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/erc721_token.ts b/packages/abi-gen-wrappers/src/generated-wrappers/erc721_token.ts
index c6bb30b16..aaae2ab76 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/erc721_token.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/erc721_token.ts
@@ -65,8 +65,11 @@ export class ERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getApproved(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public approve = {
@@ -147,8 +150,11 @@ export class ERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('approve(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferFrom = {
@@ -238,8 +244,11 @@ export class ERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferFrom(address,address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public safeTransferFrom1 = {
@@ -329,8 +338,11 @@ export class ERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('safeTransferFrom(address,address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public ownerOf = {
@@ -354,8 +366,11 @@ export class ERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('ownerOf(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public balanceOf = {
@@ -379,8 +394,11 @@ export class ERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('balanceOf(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public setApprovalForAll = {
@@ -461,8 +479,11 @@ export class ERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('setApprovalForAll(address,bool)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public safeTransferFrom2 = {
@@ -561,8 +582,11 @@ export class ERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('safeTransferFrom(address,address,uint256,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public isApprovedForAll = {
@@ -588,8 +612,11 @@ export class ERC721TokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('isApprovedForAll(address,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/exchange.ts b/packages/abi-gen-wrappers/src/generated-wrappers/exchange.ts
index 23d8f6ce4..146fa7c2a 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/exchange.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/exchange.ts
@@ -91,8 +91,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('filled(bytes32)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public batchFillOrders = {
@@ -182,8 +185,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('batchFillOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256[],bytes[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public cancelled = {
@@ -207,8 +213,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('cancelled(bytes32)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public preSign = {
@@ -298,8 +307,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('preSign(bytes32,address,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public matchOrders = {
@@ -398,8 +410,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('matchOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),(address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),bytes,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{left: {makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber};right: {makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber};leftMakerAssetSpreadAmount: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public fillOrderNoThrow = {
@@ -489,8 +504,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('fillOrderNoThrow((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),uint256,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public assetProxies = {
@@ -514,8 +532,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('assetProxies(bytes4)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public batchCancelOrders = {
@@ -587,8 +608,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('batchCancelOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public batchFillOrKillOrders = {
@@ -678,8 +702,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('batchFillOrKillOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256[],bytes[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public cancelOrdersUpTo = {
@@ -751,8 +778,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('cancelOrdersUpTo(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public batchFillOrdersNoThrow = {
@@ -842,8 +872,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('batchFillOrdersNoThrow((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256[],bytes[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getAssetProxy = {
@@ -867,8 +900,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getAssetProxy(bytes4)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transactions = {
@@ -892,8 +928,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transactions(bytes32)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public fillOrKillOrder = {
@@ -983,8 +1022,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('fillOrKillOrder((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),uint256,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public setSignatureValidatorApproval = {
@@ -1065,8 +1107,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('setSignatureValidatorApproval(address,bool)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public allowedValidators = {
@@ -1092,8 +1137,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('allowedValidators(address,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public marketSellOrders = {
@@ -1183,8 +1231,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('marketSellOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256,bytes[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getOrdersInfo = {
@@ -1208,8 +1259,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getOrdersInfo((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<Array<{orderStatus: number;orderHash: string;orderTakerAssetFilledAmount: BigNumber}>
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public preSigned = {
@@ -1235,8 +1289,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('preSigned(bytes32,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public owner = {
@@ -1258,8 +1315,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('owner()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public isValidSignature = {
@@ -1287,8 +1347,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('isValidSignature(bytes32,address,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public marketBuyOrdersNoThrow = {
@@ -1378,8 +1441,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('marketBuyOrdersNoThrow((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256,bytes[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public fillOrder = {
@@ -1469,8 +1535,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('fillOrder((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),uint256,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public executeTransaction = {
@@ -1569,8 +1638,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('executeTransaction(uint256,address,bytes,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public registerAssetProxy = {
@@ -1642,8 +1714,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('registerAssetProxy(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getOrderInfo = {
@@ -1667,8 +1742,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getOrderInfo((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes))');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{orderStatus: number;orderHash: string;orderTakerAssetFilledAmount: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public cancelOrder = {
@@ -1740,8 +1818,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('cancelOrder((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes))');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public orderEpoch = {
@@ -1767,8 +1848,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('orderEpoch(address,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public ZRX_ASSET_DATA = {
@@ -1790,8 +1874,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('ZRX_ASSET_DATA()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public marketSellOrdersNoThrow = {
@@ -1881,8 +1968,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('marketSellOrdersNoThrow((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256,bytes[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public EIP712_DOMAIN_HASH = {
@@ -1904,8 +1994,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('EIP712_DOMAIN_HASH()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public marketBuyOrders = {
@@ -1995,8 +2088,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('marketBuyOrders((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256,bytes[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public currentContextAddress = {
@@ -2018,8 +2114,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('currentContextAddress()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferOwnership = {
@@ -2091,8 +2190,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferOwnership(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public VERSION = {
@@ -2114,8 +2216,11 @@ export class ExchangeContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('VERSION()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/forwarder.ts b/packages/abi-gen-wrappers/src/generated-wrappers/forwarder.ts
index 6bfc4f2c9..530320792 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/forwarder.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/forwarder.ts
@@ -138,8 +138,11 @@ export class ForwarderContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('marketBuyOrdersWithEth((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],uint256,bytes[],(address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],bytes[],uint256,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<[{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}, {makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public withdrawAsset = {
@@ -220,8 +223,11 @@ export class ForwarderContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('withdrawAsset(bytes,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public owner = {
@@ -243,8 +249,11 @@ export class ForwarderContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('owner()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public marketSellOrdersWithEth = {
@@ -361,8 +370,11 @@ export class ForwarderContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('marketSellOrdersWithEth((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],bytes[],(address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],bytes[],uint256,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<[{makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}, {makerAssetFilledAmount: BigNumber;takerAssetFilledAmount: BigNumber;makerFeePaid: BigNumber;takerFeePaid: BigNumber}]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferOwnership = {
@@ -434,8 +446,11 @@ export class ForwarderContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferOwnership(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/i_validator.ts b/packages/abi-gen-wrappers/src/generated-wrappers/i_validator.ts
index 4735cecfa..6cb9f64fb 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/i_validator.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/i_validator.ts
@@ -40,8 +40,11 @@ export class IValidatorContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('isValidSignature(bytes32,address,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/i_wallet.ts b/packages/abi-gen-wrappers/src/generated-wrappers/i_wallet.ts
index 8885069bd..2185c7999 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/i_wallet.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/i_wallet.ts
@@ -38,8 +38,11 @@ export class IWalletContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('isValidSignature(bytes32,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/order_validator.ts b/packages/abi-gen-wrappers/src/generated-wrappers/order_validator.ts
index a2cdf33e6..366b207ad 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/order_validator.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/order_validator.ts
@@ -38,8 +38,11 @@ export class OrderValidatorContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getOrderAndTraderInfo((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<[{orderStatus: number;orderHash: string;orderTakerAssetFilledAmount: BigNumber}, {makerBalance: BigNumber;makerAllowance: BigNumber;takerBalance: BigNumber;takerAllowance: BigNumber;makerZrxBalance: BigNumber;makerZrxAllowance: BigNumber;takerZrxBalance: BigNumber;takerZrxAllowance: BigNumber}]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getBalanceAndAllowance = {
@@ -65,8 +68,11 @@ export class OrderValidatorContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getBalanceAndAllowance(address,bytes)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<[BigNumber, BigNumber]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getOrdersAndTradersInfo = {
@@ -92,8 +98,11 @@ export class OrderValidatorContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getOrdersAndTradersInfo((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],address[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<[Array<{orderStatus: number;orderHash: string;orderTakerAssetFilledAmount: BigNumber}>, Array<{makerBalance: BigNumber;makerAllowance: BigNumber;takerBalance: BigNumber;takerAllowance: BigNumber;makerZrxBalance: BigNumber;makerZrxAllowance: BigNumber;takerZrxBalance: BigNumber;takerZrxAllowance: BigNumber}>]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getTradersInfo = {
@@ -119,8 +128,11 @@ export class OrderValidatorContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getTradersInfo((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes)[],address[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<Array<{makerBalance: BigNumber;makerAllowance: BigNumber;takerBalance: BigNumber;takerAllowance: BigNumber;makerZrxBalance: BigNumber;makerZrxAllowance: BigNumber;takerZrxBalance: BigNumber;takerZrxAllowance: BigNumber}>
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getERC721TokenOwner = {
@@ -146,8 +158,11 @@ export class OrderValidatorContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getERC721TokenOwner(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getBalancesAndAllowances = {
@@ -173,8 +188,11 @@ export class OrderValidatorContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getBalancesAndAllowances(address,bytes[])');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<[BigNumber[], BigNumber[]]
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public getTraderInfo = {
@@ -200,8 +218,11 @@ export class OrderValidatorContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('getTraderInfo((address,address,address,address,uint256,uint256,uint256,uint256,uint256,uint256,bytes,bytes),address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<{makerBalance: BigNumber;makerAllowance: BigNumber;takerBalance: BigNumber;takerAllowance: BigNumber;makerZrxBalance: BigNumber;makerZrxAllowance: BigNumber;takerZrxBalance: BigNumber;takerZrxAllowance: BigNumber}
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/weth9.ts b/packages/abi-gen-wrappers/src/generated-wrappers/weth9.ts
index 7bb480968..5af169e03 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/weth9.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/weth9.ts
@@ -69,8 +69,11 @@ export class WETH9Contract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('name()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public approve = {
@@ -151,8 +154,11 @@ export class WETH9Contract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('approve(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public totalSupply = {
@@ -174,8 +180,11 @@ export class WETH9Contract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('totalSupply()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferFrom = {
@@ -265,8 +274,11 @@ export class WETH9Contract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferFrom(address,address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public withdraw = {
@@ -338,8 +350,11 @@ export class WETH9Contract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('withdraw(uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public decimals = {
@@ -361,8 +376,11 @@ export class WETH9Contract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('decimals()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<number
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public balanceOf = {
@@ -386,8 +404,11 @@ export class WETH9Contract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('balanceOf(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public symbol = {
@@ -409,8 +430,11 @@ export class WETH9Contract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('symbol()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transfer = {
@@ -491,8 +515,11 @@ export class WETH9Contract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transfer(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public deposit = {
@@ -555,8 +582,11 @@ export class WETH9Contract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('deposit()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray;
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<void
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public allowance = {
@@ -582,8 +612,11 @@ export class WETH9Contract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('allowance(address,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/abi-gen-wrappers/src/generated-wrappers/zrx_token.ts b/packages/abi-gen-wrappers/src/generated-wrappers/zrx_token.ts
index 0d9eb524f..4f5d7f4c5 100644
--- a/packages/abi-gen-wrappers/src/generated-wrappers/zrx_token.ts
+++ b/packages/abi-gen-wrappers/src/generated-wrappers/zrx_token.ts
@@ -55,8 +55,11 @@ export class ZRXTokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('name()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public approve = {
@@ -137,8 +140,11 @@ export class ZRXTokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('approve(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public totalSupply = {
@@ -160,8 +166,11 @@ export class ZRXTokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('totalSupply()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transferFrom = {
@@ -251,8 +260,11 @@ export class ZRXTokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transferFrom(address,address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public decimals = {
@@ -274,8 +286,11 @@ export class ZRXTokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('decimals()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<number
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public balanceOf = {
@@ -299,8 +314,11 @@ export class ZRXTokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('balanceOf(address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public symbol = {
@@ -322,8 +340,11 @@ export class ZRXTokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('symbol()');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<string
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public transfer = {
@@ -404,8 +425,11 @@ export class ZRXTokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('transfer(address,uint256)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<boolean
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public allowance = {
@@ -431,8 +455,11 @@ export class ZRXTokenContract extends BaseContract {
             const rawCallResult = await self._web3Wrapper.callAsync(callDataWithDefaults, defaultBlock);
             BaseContract._throwIfRevertWithReasonCallResult(rawCallResult);
             const abiEncoder = self._lookupAbiEncoder('allowance(address,address)');
-            const resultArray = abiEncoder.decodeReturnValuesAsArrayOrNull(rawCallResult);
-            return resultArray[0];
+            // tslint:disable boolean-naming
+            const result = abiEncoder.strictDecodeReturnValue<BigNumber
+        >(rawCallResult);
+            // tslint:enable boolean-naming
+            return result;
         },
     };
     public static async deployFrom0xArtifactAsync(
diff --git a/packages/utils/src/abi_encoder/evm_data_types/method.ts b/packages/utils/src/abi_encoder/evm_data_types/method.ts
index c0cf80c74..c852a0fdf 100644
--- a/packages/utils/src/abi_encoder/evm_data_types/method.ts
+++ b/packages/utils/src/abi_encoder/evm_data_types/method.ts
@@ -44,16 +44,17 @@ export class MethodDataType extends AbstractSetDataType {
         return returnValues;
     }
 
-    public decodeReturnValuesAsArray(returnData: string, rules?: DecodingRules): any[] {
-        const returnValues = this.decodeReturnValues(returnData, rules);
-        const returnValuesAsArray = _.isObject(returnValues) ? _.values(returnValues) : [returnValues];
-        return returnValuesAsArray;
-    }
-
-    public decodeReturnValuesAsArrayOrNull(returnData: string, rules?: DecodingRules): any {
-        const returnValuesAsArray = this.decodeReturnValuesAsArray(returnData, rules);
-        const returnValue = _.isEmpty(returnValuesAsArray) ? [] : returnValuesAsArray;
-        return returnValue;
+    public strictDecodeReturnValue<T>(returndata: string, rules?: DecodingRules): T {
+        const returnValues = this._returnDataType.decode(returndata, rules);
+        const returnValuesAsArray: any = _.isObject(returnValues) ? _.values(returnValues) : [returnValues];
+        switch (returnValuesAsArray.length) {
+            case 0:
+                return undefined as any;
+            case 1:
+                return returnValuesAsArray[0];
+            default:
+                return returnValuesAsArray;
+        }
     }
 
     public getSignatureType(): string {