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June 12, 2018 15:29
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Created using remix-ide: Realtime Ethereum Contract Compiler and Runtime. Load this file by pasting this gists URL or ID at https://remix.ethereum.org/#version=soljson-v0.4.23+commit.124ca40d.js&optimize=false&gist=
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pragma solidity ^0.4.0; | |
interface ERC20 { | |
function transferFrom(address _from, address _to, uint _value) public returns (bool); | |
function approve(address _spender, uint _value) public returns (bool); | |
function allowance(address _owner, address _spender) public constant returns (uint); | |
event Approval(address indexed _owner, address indexed _spender, uint _value); | |
} |
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pragma solidity ^0.4.0; | |
interface ERC223 { | |
function transfer(address _to, uint _value, bytes _data) public returns (bool); | |
event Transfer(address indexed from, address indexed to, uint value, bytes indexed data); | |
} |
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pragma solidity ^0.4.0; | |
contract ERC223ReceivingContract { | |
function tokenFallback(address _from, uint _value, bytes _data) public; | |
} |
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pragma solidity ^0.4.0; | |
import "browser/ERC20.sol"; | |
import "browser/ERC223.sol"; | |
import "browser/ERC223ReceivingContract.sol"; | |
import "browser/Token.sol"; | |
// | |
// Disadvantage of ERC20: | |
// 1. There is no check to see if we are sending the token to contract | |
// If the token gets sent to a contract, we have no way of recovering it. | |
// With Ether, if ether gets sent to a contract the transaction fails and | |
// it rolls over the state | |
// | |
// ERC223 | |
// Thats where ERC223 comes into picture, because we first check if the | |
// receiver addresss is a contract before sending | |
contract MyFirstToken is Token("MFT", "My First Token", 10, 1000), ERC20, | |
ERC223, ERC223ReceivingContract { | |
constructor() public | |
{ | |
_balanceOf[msg.sender] = _totalSupply; | |
} | |
function balanceOf(address _addr) public view returns (uint) | |
{ | |
return _balanceOf[_addr]; | |
} | |
function transfer(address _to, uint _value) public returns (bool) | |
{ | |
if (_balanceOf[msg.sender] >= _value && _value > 0 | |
&& !isContract(_to)) { | |
_balanceOf[msg.sender] -= _value; | |
_balanceOf[_to] += _value; | |
emit Transfer(msg.sender, _to, _value); | |
return true; | |
} | |
return false; | |
} | |
function transfer(address _to, uint _value, bytes _data) public returns (bool) | |
{ | |
if (_value > 0 && _balanceOf[msg.sender] >= _value | |
&& isContract(_to)) { | |
_balanceOf[msg.sender] -= _value; | |
_balanceOf[_to] += _value; | |
ERC223ReceivingContract _contract = ERC223ReceivingContract(_to); | |
_contract.tokenFallback(msg.sender, _value, _data); | |
emit Transfer(msg.sender, _to, _value); | |
return true; | |
} | |
return false; | |
} | |
function transferFrom(address _from, address _to, uint _value) public returns (bool) | |
{ | |
if (_value > 0 && _allowances[_from][_to] > _value && | |
_balanceOf[_from] > _value) { | |
_balanceOf[_from] -= _value; | |
_allowances[_from][_to] -= _value; | |
_balanceOf[_to] += _value; | |
emit Transfer(_from, _to, _value); | |
return true; | |
} | |
return false; | |
} | |
function allowance(address _owner, address _spender) public constant returns (uint) | |
{ | |
return _allowances[_owner][_spender]; | |
} | |
function approve(address _spender, uint _value) public returns (bool) | |
{ | |
_allowances[msg.sender][_spender] = _value; | |
emit Approval(msg.sender, _spender, _value); | |
return true; | |
} | |
// Check to see if the codeSize is > 0 | |
function isContract(address _addr) public view returns (bool) | |
{ | |
// assembly language | |
uint codeSize; | |
assembly { | |
codeSize := extcodesize(_addr) | |
} | |
return codeSize > 0; | |
} | |
} |
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pragma solidity ^0.4.0; | |
// Minimum viable Token | |
contract Token { | |
string internal _symbol; | |
string internal _name; | |
uint8 internal _decimal; | |
uint internal _totalSupply = 1000; | |
mapping (address => uint) internal _balanceOf; | |
mapping (address => mapping (address => uint)) internal _allowances; | |
constructor(string symbol, string name, uint8 decimal, uint totalSupply) public | |
{ | |
_symbol = symbol; | |
_name = name; | |
_decimal = decimal; | |
_totalSupply = totalSupply; | |
} | |
function name() public view returns (string) | |
{ | |
return _name; | |
} | |
function symbol() public view returns (string) | |
{ | |
return _symbol; | |
} | |
function decimal() public view returns (uint8) | |
{ | |
return _decimal; | |
} | |
function totalSupply() public view returns (uint) | |
{ | |
return _totalSupply; | |
} | |
function balanceOf(address _addr) public view returns (uint); | |
function transfer(address _to, uint _value) public returns (bool); | |
event Transfer(address indexed_from, address indexed _to, uint _value); | |
} |
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