deafultuple.py

# -*- coding: utf-8 -*-

from collections import namedtuple, Mapping

__all__ = ['defaultuple']


def defaultuple(typename, field_names, default_values=()):
    """ Build a new `namedtuple` type with optional default values that
    can be specified as positional or keyword arguments.
    """
    T = namedtuple(typename, field_names)
    T.__new__.__defaults__ = (None,) * len(T._fields)
    if isinstance(default_values, Mapping):
        prototype = T(**default_values)
    else:
        prototype = T(*default_values)
    T.__new__.__defaults__ = tuple(prototype)
    return T