Allow mapping storage parameters for library functions #4635
Closed
Description
Since library functions allow storage struct parameters, storage mapping parameters should also be allowed. This would enable us to modularize some things:
library Balances {
function send(mapping(address => uint256) storage balances, address from, address to, uint amount) internal {
require(balances[from] >= amount);
require(balances[to] + amount >= balances[to]);
balances[from] -= amount;
balances[to] += amount;
}
}
contract Token {
mapping(address => uint256) balances;
using Balances for *;
mapping(address => mapping (address => uint256)) allowed;
event Transfer(address from, address to, uint amount);
event Approval(address owner, address spender, uint amount);
function balanceOf(address tokenOwner) public constant returns (uint balance) {
return balances[tokenOwner];
}
function transfer(address to, uint amount) public returns (bool success) {
balances.send(msg.sender, to, amount);
emit Transfer(msg.sender, to, amount);
return true;
}
function transferFrom(address from, address to, uint amount) public returns (bool success) {
require(allowed[from][msg.sender] >= amount);
allowed[from][msg.sender] -= amount;
balances.send(from, to, amount);
emit Transfer(from, to, amount);
return true;
}
function approve(address spender, uint tokens) public returns (bool success) {
require(allowed[msg.sender][spender] == 0, "");
allowed[msg.sender][spender] = tokens;
emit Approval(msg.sender, spender, tokens);
return true;
}
}