ERC20.v.py

# Solidity-Compatible EIP20/ERC20 Token
# Implements https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20-token-standard.md
# Author: Phil Daian

# The use of the num256 datatype as in this token is not
# recommended, as it can pose security risks.

# This token is intended as a proof of concept towards
# language interoperability and not for production use.

# Events issued by the contract
Transfer: __log__({_from: indexed(address), _to: indexed(address), _value: num256})
Approval: __log__({_owner: indexed(address), _spender: indexed(address), _value: num256})

balances: num256[address]
allowances: (num256[address])[address]
num_issued: num256

@public
@payable
def deposit():
    _value = as_num256(msg.value)
    _sender = msg.sender
    self.balances[_sender] = num256_add(self.balances[_sender], _value)
    self.num_issued = num256_add(self.num_issued, _value)
    # Fire deposit event as transfer from 0x0
    log.Transfer(0x0000000000000000000000000000000000000000, _sender, _value)

@public
def withdraw(_value : num256) -> bool:
    _sender = msg.sender
    # Make sure sufficient funds are present, op will not underflow supply
    # implicitly through overflow protection
    self.balances[_sender] = num256_sub(self.balances[_sender], _value)
    self.num_issued = num256_sub(self.num_issued, _value)
    send(_sender, as_wei_value(as_num128(_value), wei))
    # Fire withdraw event as transfer to 0x0
    log.Transfer(_sender, 0x0000000000000000000000000000000000000000, _value)
    return true

@public
@constant
def totalSupply() -> num256:
    return self.num_issued

@public
@constant
def balanceOf(_owner : address) -> num256:
    return self.balances[_owner]

@public
def transfer(_to : address, _value : num256) -> bool:
    _sender = msg.sender
    # Make sure sufficient funds are present implicitly through overflow protection
    self.balances[_sender] = num256_sub(self.balances[_sender], _value)
    self.balances[_to] = num256_add(self.balances[_to], _value)
    # Fire transfer event
    log.Transfer(_sender, _to, _value)
    return true

@public
def transferFrom(_from : address, _to : address, _value : num256) -> bool:
    _sender = msg.sender
    allowance = self.allowances[_from][_sender]
    # Make sure sufficient funds/allowance are present implicitly through overflow protection
    self.balances[_from] = num256_sub(self.balances[_from], _value)
    self.balances[_to] = num256_add(self.balances[_to], _value)
    self.allowances[_from][_sender] = num256_sub(allowance, _value)
    # Fire transfer event
    log.Transfer(_from, _to, _value)
    return true

@public
def approve(_spender : address, _value : num256) -> bool:
    _sender = msg.sender
    self.allowances[_sender][_spender] = _value
    # Fire approval event
    log.Approval(_sender, _spender, _value)
    return true

@public
@constant
def allowance(_owner : address, _spender : address) -> num256:
    return self.allowances[_owner][_spender]