solidity语言13

solidity语言13

函数过载

合约内允许定义同名函数，但是输入参数不一致 pragma solidity ^0.4.17; contract A { function f(uint _in) public pure returns (uint out) { out = 1; } function f(uint _in, bytes32 _key) public pure returns (uint out) { out = 2; } } pragma solidity ^0.4.16; contract A { function f(B _in) public pure returns (B out) { out = _in; } function f(address _in) public pure returns (address out) { out = _in; } } contract B { }

事件

// 事件可方便使用EVM的日志工具，通过dapp的用户接口调用回调函数进行监听。 pragma solidity ^0.4.0; contract ClientReceipt { event Deposit( address indexed _from, bytes32 indexed _id, uint _value ); function deposit(bytes32 _id) public payable { // 任何调用当前函数的操作都会被检测到 Deposit(msg.sender, _id, msg.value); } } var abi = /* abi as generated by the compiler */; var ClientReceipt = web3.eth.contract(abi); var clientReceipt = ClientReceipt.at("0x1234...ab67"); /* address */ var event = clientReceipt.Deposit(); event.watch( function(error, result) { if (!error) console.log(result); }); /*或者 var event = clientReceipt.Deposit(function(error, result) { if (!error) console.log(result); }); */

使用log低层接口

log0, log1, log2, log3, log4 ~ logN pragma solidity ^0.4.10; contract C { function f() public payable { bytes32 _id = 0x420042; log3( bytes32(msg.value), bytes32(0x50cb9fe53daa9737b786ab3646f04d0150dc50ef4e75f59509d83667ad5adb20), bytes32(msg.sender), _id ); } }

用于理解事件的其他资源

接口

当合约继承其他合约，仅一个单独的合约被区位链建立，代码从基础合约复制到建立的合约中。

pragma solidity ^0.4.16; contract owned { address owner; // 构造函数 function owned() { owner = msg.sender; } } // 继承合约owned的所有属性，但不能使用通过this进行外部访问 contract mortal is owned { function kill() { if (msg.sender == owner) selfdestruct(owner); } } // These abstract contracts are only provided to make the // interface known to the compiler. Note the function // without body. If a contract does not implement all // functions it can only be used as an interface. contract Config { function lookup(uint id) public returns (address adr); } contract NameReg { function register(bytes32 name) public; function unregister() public; } contract named is owned, mortal { function named(bytes32 name) { Config config = Config(0xD5f9D8D94886E70b06E474c3fB14Fd43E2f23970); NameReg(config.lookup(1)).register(name); } function kill() public { if (msg.sender == owner) { Config config = Config(0xD5f9D8D94886E70b06E474c3fB14Fd43E2f23970); NameReg(config.lookup(1)).unregister(); mortal.kill(); } } } contract PriceFeed is owned, mortal, named("GoldFeed") { function updateInfo(uint newInfo) public { if (msg.sender == owner) info = newInfo; } function get() public view returns(uint r) { return info; } uint info; } pragma solidity ^0.4.0; contract owned { address owner; function owned() public { owner = msg.sender; } } contract mortal is owned { function kill() public { if (msg.sender == owner) selfdestruct(owner); } } contract Base1 is mortal { function kill() public { /* do cleanup 1 */ mortal.kill(); } } contract Base2 is mortal { function kill() public { /* do cleanup 2 */ mortal.kill(); } } contract Final is Base1, Base2 { } pragma solidity ^0.4.0; contract owned { function owned() public { owner = msg.sender; } address owner; } contract mortal is owned { function kill() public { if (msg.sender == owner) selfdestruct(owner); } } contract Base1 is mortal { function kill() public { /* do cleanup 1 */ super.kill(); } } contract Base2 is mortal { function kill() public { /* do cleanup 2 */ super.kill(); } } contract Final is Base1, Base2 { } posted on 2018-02-28 17:29 北京涛子 阅读( ...) 评论( ...) 编辑 收藏

转载于:https://www.cnblogs.com/liujitao79/p/8484797.html

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