Lazy chainable operator

chain.py

import operator


class Operator(object):
    '''Chaineable and lazy operations'''

    def __init__(self, value, *args):
        self._value = value
        self._args = args

    def value(self):
        if callable(self._value):
            return self._value(*map(Operator.resolve, self._args))
        return self._value

    @staticmethod
    def resolve(arg):
        if isinstance(arg, Operator):
            return arg.value()
        return arg

    def __add__(self, value):
        return Operator(operator.add, self, value)

    def __radd__(self, value):
        return Operator(operator.add, value, self)

    def __sub__(self, value):
        return Operator(operator.sub, self, value)

    def __rsub__(self, value):
        return Operator(operator.sub, value, self)

    def __mul__(self, value):
        return Operator(operator.mul, self, value)

    def __rmul__(self, value):
        return Operator(operator.mul, value, self)

    def __div__(self, value):
        return Operator(operator.div, self, value)

    def __rdiv__(self, value):
        return Operator(operator.div, value, self)

    def __repr__(self):
        if self._args:
            return 'Operator(value=%r, args=%r)' % (self._value, self._args)
        return 'Operator(%r)' % self._value

    def __str__(self):
        return str(self.value())

output.py

>>> from chain import Operator
>>> operators = [Operator(x) for x in range(10)]
>>> operators
[Operator(0), Operator(1), Operator(2), Operator(3), Operator(4), Operator(5), Operator(6), Operator(7), Operator(8), Operator(9)]
>>> sum(operators)
Operator(value=<built-in function add>, args=(Operator(value=<built-in function add>, args=(Operator(value=<built-in function add>, args=(Operator(value=<built-in function add>, args=(Operator(value=<built-in function add>, args=(Operator(value=<built-in function add>, args=(Operator(value=<built-in function add>, args=(Operator(value=<built-in function add>, args=(Operator(value=<built-in function add>, args=(Operator(value=<built-in function add>, args=(0, Operator(0))), Operator(1))), Operator(2))), Operator(3))), Operator(4))), Operator(5))), Operator(6))), Operator(7))), Operator(8))), Operator(9)))
>>> result=_
>>> result.value()
45
>>> result = Operator(1) + Operator(10) / Operator(5)
>>> result.value()
3
>>> result = Operator(1) + 10 / 5
>>> result.value()
3
>>> result = 1 + Operator(2)
>>> result.value()
3
>>> result = 1 + Operator(2) / 0
>>> result  # Because operation is lazy, exception not raised
Operator(value=<built-in function add>, args=(1, Operator(value=<built-in function div>, args=(Operator(2), 0))))
>>> result.value()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "chain.py", line 13, in value
    return self._value(*map(Operator.resolve, self._args))
  File "chain.py", line 19, in resolve
    return arg.value()
  File "chain.py", line 13, in value
    return self._value(*map(Operator.resolve, self._args))
ZeroDivisionError: integer division or modulo by zero
>>>