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authorChris Ward <chriswhward@gmail.com>2018-09-24 20:10:01 +0800
committerchriseth <chris@ethereum.org>2018-11-12 22:07:57 +0800
commit144909dfb8c0ba58d54c24e68f81db47e044913f (patch)
tree22b7c598e15657ed6a82e624cc0ba551902ffb51 /docs
parent288582e38eac70115c15c89ebbb8a7765139eaa6 (diff)
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Clarify creating a contract example as reported in #2661
Diffstat (limited to 'docs')
-rw-r--r--docs/contracts.rst33
1 files changed, 20 insertions, 13 deletions
diff --git a/docs/contracts.rst b/docs/contracts.rst
index d4160eac..4d439b26 100644
--- a/docs/contracts.rst
+++ b/docs/contracts.rst
@@ -50,7 +50,7 @@ This means that cyclic creation dependencies are impossible.
pragma solidity >=0.4.22 <0.6.0;
contract OwnedToken {
- // TokenCreator is a contract type that is defined below.
+ // `TokenCreator` is a contract type that is defined below.
// It is fine to reference it as long as it is not used
// to create a new contract.
TokenCreator creator;
@@ -61,14 +61,18 @@ This means that cyclic creation dependencies are impossible.
// creator and the assigned name.
constructor(bytes32 _name) public {
// State variables are accessed via their name
- // and not via e.g. this.owner. This also applies
- // to functions and especially in the constructors,
- // you can only call them like that ("internally"),
- // because the contract itself does not exist yet.
+ // and not via e.g. `this.owner`. Functions can
+ // be accessed directly or through `this.f`,
+ // but the latter provides an external view
+ // to the function. Especially in the constructor,
+ // you should not access functions externally,
+ // because the function does not exist yet.
+ // See the next section for details.
owner = msg.sender;
+
// We do an explicit type conversion from `address`
// to `TokenCreator` and assume that the type of
- // the calling contract is TokenCreator, there is
+ // the calling contract is `TokenCreator`, there is
// no real way to check that.
creator = TokenCreator(msg.sender);
name = _name;
@@ -86,10 +90,11 @@ This means that cyclic creation dependencies are impossible.
// Only the current owner can transfer the token.
if (msg.sender != owner) return;
- // We also want to ask the creator if the transfer
- // is fine. Note that this calls a function of the
- // contract defined below. If the call fails (e.g.
- // due to out-of-gas), the execution also fails here.
+ // We ask the creator contract if the transfer
+ // should proceed by using a function of the
+ // `TokenCreator` contract defined below. If
+ // the call fails (e.g. due to out-of-gas),
+ // the execution also fails here.
if (creator.isTokenTransferOK(owner, newOwner))
owner = newOwner;
}
@@ -100,8 +105,8 @@ This means that cyclic creation dependencies are impossible.
public
returns (OwnedToken tokenAddress)
{
- // Create a new Token contract and return its address.
- // From the JavaScript side, the return type is simply
+ // Create a new `Token` contract and return its address.
+ // From the JavaScript side, the return type is
// `address`, as this is the closest type available in
// the ABI.
return new OwnedToken(name);
@@ -113,12 +118,14 @@ This means that cyclic creation dependencies are impossible.
tokenAddress.changeName(name);
}
+ // Perform checks to determine if transferring a token to the
+ // `OwnedToken` contract should proceed
function isTokenTransferOK(address currentOwner, address newOwner)
public
pure
returns (bool ok)
{
- // Check some arbitrary condition.
+ // Check an arbitrary condition to see if transfer should proceed
return keccak256(abi.encodePacked(currentOwner, newOwner))[0] == 0x7f;
}
}