部署智能合约初试（第一个是wbtc）
wbtc合约解读
如果不了解方法，就是用remix部署成功或恢复出来后，除了最简单的mint, burn, transfer, balancesOf等外，你依然很懵逼。
想完整了解wbtc的用法，就需要读代码。当然，你还得对solidity语法有足够了解（还有solidity语法1-2天也就看完了）
下面是主要的写方法：
mint, burn, transfer 都比较简单，忽略
一、approve授权相关
场景：假设A是Owner，授权B一定数量的token，然后B就可以使用授权的token
approve(_spender, uint256)【操作】
transferFrom(_from, _to, _value) 【操作】
allowance(_owner, _spender) view 【查看】检查owner允许给spender使用的代币数量
decreaseApproval(_spender, uint256)【操作】
increaseApproval(_spender, uint256)【操作】
transferFrom这样搞：假设账户A有1000个ETH，想允许B账户随意调用他的100个ETH，过程如下：
1、A账户按照以下形式调用approve函数approve(B,100)
2、B账户想用这100个ETH中的10个ETH给C账户，调用transferFrom(A, C, 10)
3、调用allowance(A, B)可以查看B账户还能够调用A账户多少个token
二、转移币对所有权
场景：A是Owner，把所有权转给B
transferOwnership(_newOwner) onlyOwner【操作】
claimOwnership() onlyPendingOwner
claimOwnership的执行这样搞：
1、使用合约的owner执行transferOwnership，把ownership转移给newOwner
2、使用newOwner执行claimOwnership方法
renounceOwnership() onlyOwner【操作】 放弃所有权
三、收回token
reclaimToken(_token) onlyOwner【操作】 合约收到的转账，可以通过这个命令把转账的token提到owenr的地址
--------第一次学习--------
前提：需要熟悉metamask。浏览器插件或APP客户端。
1，查看wbtc源码
GitHub：https://github.com/WrappedBTC
在etherscan上搜索：wbtc
https://cn.etherscan.com/token/0x2260fac5e5542a773aa44fbcfedf7c193bc2c599#readContract
点击右侧Contract的地址，进入查看合约详情页面：
https://cn.etherscan.com/address/0x2260fac5e5542a773aa44fbcfedf7c193bc2c599#code
找到合约源码。
2，remix
部署教程：
https://www.bilibili.com/video/av542138968
主要分三步，如红框所示：
第一步，贴源码，或自己写源码。在右侧页签为当前选中状态。
第二步，配置编译环境：compiler选择与wbtc官方对应的版本，点击编译。
第三步，Environment选择Injected Web3，Contract选择WBTC，点击deploy。注意：如果部署多次，就会生成多个，每个以合约地址区分。
在右下方生成：Deployed Contracts
当然，如果是第二次打开，还可以通过合约地址恢复。
如图所示：deploy和At Address二选一。
部署/恢复 成功后，在Deployed Contracts下有里面的相关方法。其中黄色是写操作（上链），蓝色是读操作（不上链）
方法都列出了。
但这里有一个缺点，就是这些方法间没有逻辑关系，想熟练使用就得对每一个方法都很熟悉，包括参数和返回值。（只能看代码了）
并且，有些方法只能组合用，也需要你自己把逻辑提前搞清楚。
3，安装truffle
npm install -g truffle
truffle watch # 监控文件系统的文件变化，重编译，重部署你的合约。在被修改后需要的时候，会重构建前端代码。
truffle serve # 监控文件系统的变化，重编译，部署，构建，并在http://localhost:8080/提供服务。
附wbtc源码：
/** *Submitted for verification at Etherscan.io on 2018-11-24 */ pragma solidity 0.4.24; // File: openzeppelin-solidity/contracts/token/ERC20/ERC20Basic.sol /** * @title ERC20Basic * @dev Simpler version of ERC20 interface * See https://github.com/ethereum/EIPs/issues/179 */ contract ERC20Basic { function totalSupply() public view returns (uint256); function balanceOf(address _who) public view returns (uint256); function transfer(address _to, uint256 _value) public returns (bool); event Transfer(address indexed from, address indexed to, uint256 value); } // File: openzeppelin-solidity/contracts/math/SafeMath.sol /** * @title SafeMath * @dev Math operations with safety checks that throw on error */ library SafeMath { /** * @dev Multiplies two numbers, throws on overflow. */ function mul(uint256 _a, uint256 _b) internal pure returns (uint256 c) { // Gas optimization: this is cheaper than asserting 'a' not being zero, but the // benefit is lost if 'b' is also tested. // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522 if (_a == 0) { return 0; } c = _a * _b; assert(c / _a == _b); return c; } /** * @dev Integer division of two numbers, truncating the quotient. */ function div(uint256 _a, uint256 _b) internal pure returns (uint256) { // assert(_b > 0); // Solidity automatically throws when dividing by 0 // uint256 c = _a / _b; // assert(_a == _b * c + _a % _b); // There is no case in which this doesn't hold return _a / _b; } /** * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend). */ function sub(uint256 _a, uint256 _b) internal pure returns (uint256) { assert(_b <= _a); return _a - _b; } /** * @dev Adds two numbers, throws on overflow. */ function add(uint256 _a, uint256 _b) internal pure returns (uint256 c) { c = _a + _b; assert(c >= _a); return c; } } // File: openzeppelin-solidity/contracts/token/ERC20/BasicToken.sol /** * @title Basic token * @dev Basic version of StandardToken, with no allowances. */ contract BasicToken is ERC20Basic { using SafeMath for uint256; mapping(address => uint256) internal balances; uint256 internal totalSupply_; /** * @dev Total number of tokens in existence */ function totalSupply() public view returns (uint256) { return totalSupply_; } /** * @dev Transfer token for a specified address * @param _to The address to transfer to. * @param _value The amount to be transferred. */ function transfer(address _to, uint256 _value) public returns (bool) { require(_value <= balances[msg.sender]); require(_to != address(0)); balances[msg.sender] = balances[msg.sender].sub(_value); balances[_to] = balances[_to].add(_value); emit Transfer(msg.sender, _to, _value); return true; } /** * @dev Gets the balance of the specified address. * @param _owner The address to query the the balance of. * @return An uint256 representing the amount owned by the passed address. */ function balanceOf(address _owner) public view returns (uint256) { return balances[_owner]; } } // File: openzeppelin-solidity/contracts/token/ERC20/ERC20.sol /** * @title ERC20 interface * @dev see https://github.com/ethereum/EIPs/issues/20 */ contract ERC20 is ERC20Basic { function allowance(address _owner, address _spender) public view returns (uint256); function transferFrom(address _from, address _to, uint256 _value) public returns (bool); function approve(address _spender, uint256 _value) public returns (bool); event Approval( address indexed owner, address indexed spender, uint256 value ); } // File: openzeppelin-solidity/contracts/token/ERC20/StandardToken.sol /** * @title Standard ERC20 token * * @dev Implementation of the basic standard token. * https://github.com/ethereum/EIPs/issues/20 * Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol */ contract StandardToken is ERC20, BasicToken { mapping (address => mapping (address => uint256)) internal allowed; /** * @dev Transfer tokens from one address to another * @param _from address The address which you want to send tokens from * @param _to address The address which you want to transfer to * @param _value uint256 the amount of tokens to be transferred */ function transferFrom( address _from, address _to, uint256 _value ) public returns (bool) { require(_value <= balances[_from]); require(_value <= allowed[_from][msg.sender]); require(_to != address(0)); balances[_from] = balances[_from].sub(_value); balances[_to] = balances[_to].add(_value); allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value); emit Transfer(_from, _to, _value); return true; } /** * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender. * Beware that changing an allowance with this method brings the risk that someone may use both the old * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards: * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729 * @param _spender The address which will spend the funds. * @param _value The amount of tokens to be spent. */ function approve(address _spender, uint256 _value) public returns (bool) { allowed[msg.sender][_spender] = _value; emit Approval(msg.sender, _spender, _value); return true; } /** * @dev Function to check the amount of tokens that an owner allowed to a spender. * @param _owner address The address which owns the funds. * @param _spender address The address which will spend the funds. * @return A uint256 specifying the amount of tokens still available for the spender. */ function allowance( address _owner, address _spender ) public view returns (uint256) { return allowed[_owner][_spender]; } /** * @dev Increase the amount of tokens that an owner allowed to a spender. * approve should be called when allowed[_spender] == 0. To increment * allowed value is better to use this function to avoid 2 calls (and wait until * the first transaction is mined) * From MonolithDAO Token.sol * @param _spender The address which will spend the funds. * @param _addedValue The amount of tokens to increase the allowance by. */ function increaseApproval( address _spender, uint256 _addedValue ) public returns (bool) { allowed[msg.sender][_spender] = ( allowed[msg.sender][_spender].add(_addedValue)); emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]); return true; } /** * @dev Decrease the amount of tokens that an owner allowed to a spender. * approve should be called when allowed[_spender] == 0. To decrement * allowed value is better to use this function to avoid 2 calls (and wait until * the first transaction is mined) * From MonolithDAO Token.sol * @param _spender The address which will spend the funds. * @param _subtractedValue The amount of tokens to decrease the allowance by. */ function decreaseApproval( address _spender, uint256 _subtractedValue ) public returns (bool) { uint256 oldValue = allowed[msg.sender][_spender]; if (_subtractedValue >= oldValue) { allowed[msg.sender][_spender] = 0; } else { allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue); } emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]); return true; } } // File: openzeppelin-solidity/contracts/token/ERC20/DetailedERC20.sol /** * @title DetailedERC20 token * @dev The decimals are only for visualization purposes. * All the operations are done using the smallest and indivisible token unit, * just as on Ethereum all the operations are done in wei. */ contract DetailedERC20 is ERC20 { string public name; string public symbol; uint8 public decimals; constructor(string _name, string _symbol, uint8 _decimals) public { name = _name; symbol = _symbol; decimals = _decimals; } } // File: openzeppelin-solidity/contracts/ownership/Ownable.sol /** * @title Ownable * @dev The Ownable contract has an owner address, and provides basic authorization control * functions, this simplifies the implementation of "user permissions". */ contract Ownable { address public owner; event OwnershipRenounced(address indexed previousOwner); event OwnershipTransferred( address indexed previousOwner, address indexed newOwner ); /** * @dev The Ownable constructor sets the original `owner` of the contract to the sender * account. */ constructor() public { owner = msg.sender; } /** * @dev Throws if called by any account other than the owner. */ modifier onlyOwner() { require(msg.sender == owner); _; } /** * @dev Allows the current owner to relinquish control of the contract. * @notice Renouncing to ownership will leave the contract without an owner. * It will not be possible to call the functions with the `onlyOwner` * modifier anymore. */ function renounceOwnership() public onlyOwner { emit OwnershipRenounced(owner); owner = address(0); } /** * @dev Allows the current owner to transfer control of the contract to a newOwner. * @param _newOwner The address to transfer ownership to. */ function transferOwnership(address _newOwner) public onlyOwner { _transferOwnership(_newOwner); } /** * @dev Transfers control of the contract to a newOwner. * @param _newOwner The address to transfer ownership to. */ function _transferOwnership(address _newOwner) internal { require(_newOwner != address(0)); emit OwnershipTransferred(owner, _newOwner); owner = _newOwner; } } // File: openzeppelin-solidity/contracts/token/ERC20/MintableToken.sol /** * @title Mintable token * @dev Simple ERC20 Token example, with mintable token creation * Based on code by TokenMarketNet: https://github.com/TokenMarketNet/ico/blob/master/contracts/MintableToken.sol */ contract MintableToken is StandardToken, Ownable { event Mint(address indexed to, uint256 amount); event MintFinished(); bool public mintingFinished = false; modifier canMint() { require(!mintingFinished); _; } modifier hasMintPermission() { require(msg.sender == owner); _; } /** * @dev Function to mint tokens * @param _to The address that will receive the minted tokens. * @param _amount The amount of tokens to mint. * @return A boolean that indicates if the operation was successful. */ function mint( address _to, uint256 _amount ) public hasMintPermission canMint returns (bool) { totalSupply_ = totalSupply_.add(_amount); balances[_to] = balances[_to].add(_amount); emit Mint(_to, _amount); emit Transfer(address(0), _to, _amount); return true; } /** * @dev Function to stop minting new tokens. * @return True if the operation was successful. */ function finishMinting() public onlyOwner canMint returns (bool) { mintingFinished = true; emit MintFinished(); return true; } } // File: openzeppelin-solidity/contracts/token/ERC20/BurnableToken.sol /** * @title Burnable Token * @dev Token that can be irreversibly burned (destroyed). */ contract BurnableToken is BasicToken { event Burn(address indexed burner, uint256 value); /** * @dev Burns a specific amount of tokens. * @param _value The amount of token to be burned. */ function burn(uint256 _value) public { _burn(msg.sender, _value); } function _burn(address _who, uint256 _value) internal { require(_value <= balances[_who]); // no need to require value <= totalSupply, since that would imply the // sender's balance is greater than the totalSupply, which *should* be an assertion failure balances[_who] = balances[_who].sub(_value); totalSupply_ = totalSupply_.sub(_value); emit Burn(_who, _value); emit Transfer(_who, address(0), _value); } } // File: openzeppelin-solidity/contracts/lifecycle/Pausable.sol /** * @title Pausable * @dev Base contract which allows children to implement an emergency stop mechanism. */ contract Pausable is Ownable { event Pause(); event Unpause(); bool public paused = false; /** * @dev Modifier to make a function callable only when the contract is not paused. */ modifier whenNotPaused() { require(!paused); _; } /** * @dev Modifier to make a function callable only when the contract is paused. */ modifier whenPaused() { require(paused); _; } /** * @dev called by the owner to pause, triggers stopped state */ function pause() public onlyOwner whenNotPaused { paused = true; emit Pause(); } /** * @dev called by the owner to unpause, returns to normal state */ function unpause() public onlyOwner whenPaused { paused = false; emit Unpause(); } } // File: openzeppelin-solidity/contracts/token/ERC20/PausableToken.sol /** * @title Pausable token * @dev StandardToken modified with pausable transfers. **/ contract PausableToken is StandardToken, Pausable { function transfer( address _to, uint256 _value ) public whenNotPaused returns (bool) { return super.transfer(_to, _value); } function transferFrom( address _from, address _to, uint256 _value ) public whenNotPaused returns (bool) { return super.transferFrom(_from, _to, _value); } function approve( address _spender, uint256 _value ) public whenNotPaused returns (bool) { return super.approve(_spender, _value); } function increaseApproval( address _spender, uint _addedValue ) public whenNotPaused returns (bool success) { return super.increaseApproval(_spender, _addedValue); } function decreaseApproval( address _spender, uint _subtractedValue ) public whenNotPaused returns (bool success) { return super.decreaseApproval(_spender, _subtractedValue); } } // File: openzeppelin-solidity/contracts/ownership/Claimable.sol /** * @title Claimable * @dev Extension for the Ownable contract, where the ownership needs to be claimed. * This allows the new owner to accept the transfer. */ contract Claimable is Ownable { address public pendingOwner; /** * @dev Modifier throws if called by any account other than the pendingOwner. */ modifier onlyPendingOwner() { require(msg.sender == pendingOwner); _; } /** * @dev Allows the current owner to set the pendingOwner address. * @param newOwner The address to transfer ownership to. */ function transferOwnership(address newOwner) public onlyOwner { pendingOwner = newOwner; } /** * @dev Allows the pendingOwner address to finalize the transfer. */ function claimOwnership() public onlyPendingOwner { emit OwnershipTransferred(owner, pendingOwner); owner = pendingOwner; pendingOwner = address(0); } } // File: openzeppelin-solidity/contracts/token/ERC20/SafeERC20.sol /** * @title SafeERC20 * @dev Wrappers around ERC20 operations that throw on failure. * To use this library you can add a `using SafeERC20 for ERC20;` statement to your contract, * which allows you to call the safe operations as `token.safeTransfer(...)`, etc. */ library SafeERC20 { function safeTransfer( ERC20Basic _token, address _to, uint256 _value ) internal { require(_token.transfer(_to, _value)); } function safeTransferFrom( ERC20 _token, address _from, address _to, uint256 _value ) internal { require(_token.transferFrom(_from, _to, _value)); } function safeApprove( ERC20 _token, address _spender, uint256 _value ) internal { require(_token.approve(_spender, _value)); } } // File: openzeppelin-solidity/contracts/ownership/CanReclaimToken.sol /** * @title Contracts that should be able to recover tokens * @author SylTi * @dev This allow a contract to recover any ERC20 token received in a contract by transferring the balance to the contract owner. * This will prevent any accidental loss of tokens. */ contract CanReclaimToken is Ownable { using SafeERC20 for ERC20Basic; /** * @dev Reclaim all ERC20Basic compatible tokens * @param _token ERC20Basic The address of the token contract */ function reclaimToken(ERC20Basic _token) external onlyOwner { uint256 balance = _token.balanceOf(this); _token.safeTransfer(owner, balance); } } // File: contracts/utils/OwnableContract.sol // empty block is used as this contract just inherits others. contract OwnableContract is CanReclaimToken, Claimable { } /* solhint-disable-line no-empty-blocks */ // File: contracts/token/WBTC.sol contract WBTC is StandardToken, DetailedERC20("Wrapped BTC", "WBTC", 8), MintableToken, BurnableToken, PausableToken, OwnableContract { function burn(uint value) public onlyOwner { super.burn(value); } function finishMinting() public onlyOwner returns (bool) { return false; } function renounceOwnership() public onlyOwner { revert("renouncing ownership is blocked"); } }
