通过部署 ERC20 代币 sol 发出警告，

Question

我想部署我的合约，但是我有很多警告，我不知道每一个意思。

Gas requirement of function SpastToken.increaseApproval(address,uint256) high. (11 times in other functions) BasicToken.balanceOf(address) : Variables have very similar names balance and balances. Note: Modifiers are currently not considered by this static analysis.

Use assert(x) if you never ever want x to be false, not in any circumstance (apart from a bug in your code). Use require(x) if x can be false, due to e.g. invalid input or a failing external component.

contract Ownable {
address public owner;
event OwnershipTransferred(address indexed previousOwner, address indexed 
newOwner);

constructor() public {
owner = msg.sender;
}

modifier onlyOwner() {
require(msg.sender == owner);
_;
}

function transferOwnership(address newOwner) public onlyOwner {
require(newOwner != address(0));
emit OwnershipTransferred(owner, newOwner);
owner = newOwner;
}

}

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);
}

/**
* @title ERC20 interface
*/
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);
}
/**
* @title Basic token
*/
contract BasicToken is ERC20Basic {
using SafeMath for uint256;

mapping(address => uint256) balances;

uint256 totalSupply_;

function totalSupply() public view returns (uint256) {
return totalSupply_;
}

function transfer(address _to, uint256 _value) public returns (bool) {
require(_to != address(0));
require(_value <= balances[msg.sender]);
balances[msg.sender] = balances[msg.sender].sub(_value);
balances[_to] = balances[_to].add(_value);
emit Transfer(msg.sender, _to, _value);
return true;
}

function balanceOf(address _owner) public view returns (uint256 balance) {
return balances[_owner];
}
}

/**
* @title Standard ERC20 token
*/
contract StandardToken is ERC20, BasicToken {
mapping (address => mapping (address => uint256)) internal allowed;
function transferFrom(address _from, address _to, uint256 _value) public 
returns (bool) {
require(_to != address(0));
require(_value <= balances[_from]);
require(_value <= allowed[_from][msg.sender]);

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;
}

function approve(address _spender, uint256 _value) public returns (bool) {
allowed[msg.sender][_spender] = _value;
emit Approval(msg.sender, _spender, _value);
return true;
}

function allowance(address _owner, address _spender) public view returns 
(uint256) {
return allowed[_owner][_spender];
}
function increaseApproval(address _spender, uint _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;
}
function decreaseApproval(address _spender, uint _subtractedValue) public 
returns (bool) {
uint 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;
}

}

contract SpastToken is StandardToken, Ownable {

string public name;
string public symbol;
uint8 public decimals;
uint256 public initialSupply;

constructor() public {
name = 'SPAST-Coin';
symbol = 'SPAS';
decimals = 18;
initialSupply = 100000000 * 10 ** uint256(decimals);
totalSupply_ = initialSupply;
balances[owner] = initialSupply;
emit Transfer(0x0, owner, initialSupply);
}
}

Answer 1

我认为这些警告是不言自明的。除了关于断言的最后一个。那基本上说你应该使用 assert() 检查代码中的逻辑错误（那将是你做错的事情），而你应该使用 require() 检查输入是否合法（那将是呼叫者的错误）。我不认为其余的警告可以进一步解释，考虑用谷歌搜索它们。然而，带有变量名的那个只是为了帮助您避免类似变量名的拼写错误，并且不会以任何方式影响执行。此处未出现的修饰符警告试图告诉您，您可以为您的函数使用更严格的修饰符，这同样会使代码阅读更简单。

通过部署 ERC20 代币 sol 发出警告，

Warnings by deploying ERC20 token sol,

deployment

solidity

erc20