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Diffstat (limited to 'docs/contracts.rst')
| -rw-r--r-- | docs/contracts.rst | 71 |
1 files changed, 28 insertions, 43 deletions
diff --git a/docs/contracts.rst b/docs/contracts.rst index 19eba047..53e50656 100644 --- a/docs/contracts.rst +++ b/docs/contracts.rst @@ -301,10 +301,10 @@ inheritable properties of contracts and may be overridden by derived contracts. :: - pragma solidity ^0.4.22; + pragma solidity >0.4.24; contract owned { - function owned() public { owner = msg.sender; } + constructor() public { owner = msg.sender; } address owner; // This contract only defines a modifier but does not use @@ -346,7 +346,7 @@ inheritable properties of contracts and may be overridden by derived contracts. mapping (address => bool) registeredAddresses; uint price; - function Register(uint initialPrice) public { price = initialPrice; } + constructor(uint initialPrice) public { price = initialPrice; } // It is important to also provide the // `payable` keyword here, otherwise the function will @@ -473,7 +473,7 @@ The following statements are considered modifying the state: } .. note:: - ``constant`` on functions is an alias to ``view``, but this is deprecated and will be dropped in version 0.5.0. + ``constant`` on functions used to be an alias to ``view``, but this was dropped in version 0.5.0. .. note:: Getter methods are marked ``view``. @@ -485,9 +485,6 @@ The following statements are considered modifying the state: prevent modifications to the state on the level of the EVM by adding ``pragma experimental "v0.5.0";`` -.. warning:: - The compiler does not enforce yet that a ``view`` method is not modifying state. It raises a warning though. - .. index:: ! pure function, function;pure .. _pure-functions: @@ -529,12 +526,15 @@ In addition to the list of state modifying statements explained above, the follo It is a non-circumventable runtime checks done by the EVM. .. warning:: - Before version 0.4.17 the compiler didn't enforce that ``pure`` is not reading the state. + Before version 0.4.17 the compiler did not enforce that ``pure`` is not reading the state. It is a compile-time type check, which can be circumvented doing invalid explicit conversions between contract types, because the compiler can verify that the type of the contract does not do state-changing operations, but it cannot check that the contract that will be called at runtime is actually of that type. +.. warning:: + Before version 0.5.0 the compiler did not enforce that ``view`` is not writing the state. + .. index:: ! fallback function, function;fallback .. _fallback-function: @@ -543,7 +543,7 @@ Fallback Function ================= A contract can have exactly one unnamed function. This function cannot have -arguments and cannot return anything. +arguments, cannot return anything and has to have ``external`` visibility. It is executed on a call to the contract if none of the other functions match the given function identifier (or if no data was supplied at all). @@ -591,7 +591,7 @@ Like any function, the fallback function can execute complex operations as long // Sending Ether to this contract will cause an exception, // because the fallback function does not have the `payable` // modifier. - function() public { x = 1; } + function() external { x = 1; } uint x; } @@ -599,7 +599,7 @@ Like any function, the fallback function can execute complex operations as long // This contract keeps all Ether sent to it with no way // to get it back. contract Sink { - function() public payable { } + function() external payable { } } contract Caller { @@ -990,7 +990,7 @@ default constructor: ``contructor() public {}``. :: - pragma solidity ^0.4.22; + pragma solidity >0.4.24; contract A { uint public a; @@ -1006,24 +1006,8 @@ default constructor: ``contructor() public {}``. A constructor set as ``internal`` causes the contract to be marked as :ref:`abstract <abstract-contract>`. -.. note :: - Prior to version 0.4.22, constructors were defined as functions with the same name as the contract. This syntax is now deprecated. - -:: - - pragma solidity ^0.4.11; - - contract A { - uint public a; - - function A(uint _a) internal { - a = _a; - } - } - - contract B is A(1) { - function B() public {} - } +.. warning :: + Prior to version 0.4.22, constructors were defined as functions with the same name as the contract. This syntax was deprecated and is not allowed anymore in version 0.5.0. .. index:: ! base;constructor @@ -1344,9 +1328,9 @@ custom types without the overhead of external function calls: using BigInt for BigInt.bigint; function f() public pure { - var x = BigInt.fromUint(7); - var y = BigInt.fromUint(uint(-1)); - var z = x.add(y); + BigInt.bigint memory x = BigInt.fromUint(7); + BigInt.bigint memory y = BigInt.fromUint(uint(-1)); + BigInt.bigint memory z = x.add(y); } } @@ -1404,22 +1388,23 @@ Using For The directive ``using A for B;`` can be used to attach library functions (from the library ``A``) to any type (``B``). These functions will receive the object they are called on -as their first parameter (like the ``self`` variable in -Python). +as their first parameter (like the ``self`` variable in Python). The effect of ``using A for *;`` is that the functions from -the library ``A`` are attached to any type. +the library ``A`` are attached to *any* type. -In both situations, all functions, even those where the -type of the first parameter does not match the type of -the object, are attached. The type is checked at the +In both situations, *all* functions in the library are attached, +even those where the type of the first parameter does not +match the type of the object. The type is checked at the point the function is called and function overload resolution is performed. -The ``using A for B;`` directive is active for the current -scope, which is limited to a contract for now but will -be lifted to the global scope later, so that by including -a module, its data types including library functions are +The ``using A for B;`` directive is active only within the current +contract, including within all of its functions, and has no effect +outside of the contract in which it is used. The directive +may only be used inside a contract, not inside any of its functions. + +By including a library, its data types including library functions are available without having to add further code. Let us rewrite the set example from the |