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Diffstat (limited to 'docs/common-patterns.rst')
| -rw-r--r-- | docs/common-patterns.rst | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/docs/common-patterns.rst b/docs/common-patterns.rst index 739e136f..84c18936 100644 --- a/docs/common-patterns.rst +++ b/docs/common-patterns.rst @@ -13,11 +13,11 @@ Withdrawal from Contracts The recommended method of sending funds after an effect is using the withdrawal pattern. Although the most intuitive method of sending Ether, as a result of an effect, is a -direct ``send`` call, this is not recommended as it +direct ``transfer`` call, this is not recommended as it introduces a potential security risk. You may read more about this on the :ref:`security_considerations` page. -This is an example of the withdrawal pattern in practice in +The following is an example of the withdrawal pattern in practice in a contract where the goal is to send the most money to the contract in order to become the "richest", inspired by `King of the Ether <https://www.kingoftheether.com/>`_. @@ -28,7 +28,7 @@ become the new richest. :: - pragma solidity ^0.4.11; + pragma solidity >0.4.99 <0.6.0; contract WithdrawalContract { address public richest; @@ -36,7 +36,7 @@ become the new richest. mapping (address => uint) pendingWithdrawals; - function WithdrawalContract() public payable { + constructor() public payable { richest = msg.sender; mostSent = msg.value; } @@ -65,13 +65,13 @@ This is as opposed to the more intuitive sending pattern: :: - pragma solidity ^0.4.11; + pragma solidity >0.4.99 <0.6.0; contract SendContract { - address public richest; + address payable public richest; uint public mostSent; - function SendContract() public payable { + constructor() public payable { richest = msg.sender; mostSent = msg.value; } @@ -93,7 +93,7 @@ Notice that, in this example, an attacker could trap the contract into an unusable state by causing ``richest`` to be the address of a contract that has a fallback function which fails (e.g. by using ``revert()`` or by just -consuming more than the 2300 gas stipend). That way, +consuming more than the 2300 gas stipend transferred to them). That way, whenever ``transfer`` is called to deliver funds to the "poisoned" contract, it will fail and thus also ``becomeRichest`` will fail, with the contract being stuck forever. @@ -130,7 +130,7 @@ restrictions highly readable. :: - pragma solidity ^0.4.22; + pragma solidity >=0.4.22 <0.6.0; contract AccessRestriction { // These will be assigned at the construction @@ -198,7 +198,7 @@ restrictions highly readable. ); _; if (msg.value > _amount) - msg.sender.send(msg.value - _amount); + msg.sender.transfer(msg.value - _amount); } function forceOwnerChange(address _newOwner) @@ -282,7 +282,7 @@ function finishes. :: - pragma solidity ^0.4.22; + pragma solidity >=0.4.22 <0.6.0; contract StateMachine { enum Stages { |