namedtuple with type casts

crazytuple.py

from collections import namedtuple


def nocast(x):
    return x


def crazytuple(name, fields, casts):
    _tuple = namedtuple(name, fields)
    class _casting_tuple(_tuple):
        def __new__(cls, *args, **kwargs):
            args = [casts.get(f, nocast)(v) for f, v in zip(cls._fields, args)]
            kwargs = {f: casts.get(f, nocast)(v) for f, v in kwargs.items()}
            return super(_casting_tuple, cls).__new__(cls, *args, **kwargs)
    return _casting_tuple


Foo = crazytuple('Foo', ['a', 'b'], {'b': float})
print(Foo(1, 2))
# Foo(a=1, b=2.0)