SatoshiField implementation

SatoshiField.py

import decimal

class Satoshify(object):
    '''Helper class to convert from "satoshi" notation to decimal notation.'''
    DECIMAL_PLACES = 8
    DIVISOR = 10**DECIMAL_PLACES

    @classmethod
    def to_sats(cls, num):
        return num * cls.DIVISOR

    @classmethod
    def from_sats(cls, num):
        c = decimal.Context(prec=cls.DECIMAL_PLACES)
        n = decimal.Decimal(num, c) / cls.DIVISOR
        return n


class BaseSatoshiField(object):
    def __init__(self, attr, *args, **kwargs):
        self.attr = attr

    def to_property(self, **kwargs):
        getter = self.make_getter()
        setter = None
        deleter = None
        docstring = None

        if kwargs.get('setter', True):
            setter = self.make_setter()

        if kwargs.get('deleter', True):
            deleter = None

        docstring = kwargs.get('doc')

        funcs = [getter, setter, deleter, docstring]

        return property(*funcs)

    def make_getter(self):
        def wrapped_getter(newself):
            orig = getattr(newself, self.attr)
            return Satoshify.from_sats(orig)
        return wrapped_getter

    def make_setter(self):
        def wrapped_setter(newself, orig):
            value = Satoshify.to_sats(orig)
            setattr(newself, self.attr, value)
        return wrapped_setter

    def getter(self, newself):
        call = self.make_getter()
        return call(newself)

    def setter(self, newself, value):
        call = self.make_setter()
        return call(newself, value)


def SatoshiField(attrib, **kwargs):
    '''
    Returns a *virtual* 'dependant' Django field that converts from satoshis 
    (original field) to decimal notation.
    Usage:
    # Your model fields... resumed for brevity
    satoshis = models.BigIntegerField(default=0)
    coins = SatoshiField('satoshis')
    # ---
    model.satoshis = 1000
    print(model.coins) # prints 0.0001000
    model.coins = 0.5
    print(model.satoshis) # prints 50000000
    '''
    return BaseSatoshiField(attrib).to_property(**kwargs)