Named Tuple configurable defaults

named_tuple_no_defaults.py

# Based on code found @ https://stackoverflow.com/a/18348004/7513482

import collections
import sys


def namedtuple_with_defaults(typename, field_names, default_values=(), verbose=False, rename=False, module=None):
    """
    Create a namedtuple object with customizable defaults.
    Returns a new tuple subclass named typename

    :param typename: Name of the tuple subclass created
    :param field_names: (str): Space separated list of class attributes
    :param default_values: (dict,list,tuple):  Setup default values
    :param verbose: (bool): Print class definition after build. Outdated, use _source instead.
    :param rename: Automatically rename invalid fieldnames (i.e. 'def') to positional arguments rather than fail.
    :param module: If module is defined, the __module__ attribute of the named tuple is set to that value.
    :return: typename(tuple)

    Note: If you wish to see the source, call print(Friend._source) after examples below from python interpreter.
    """
    opts = {'verbose': verbose, 'rename': rename, 'module': module}
    # Fix for Python < 3.6, < 3.1
    py_version = int(''.join(map(str, sys.version_info[:2])))  # Python 2.7 becomes 27, 3.5 = 35, etc.
    if py_version < 31:
        # Verbose option was added in 3.1
        opts = {'verbose': verbose, 'rename': rename}

    elif py_version < 36:
        # Module was added in 3.6
        del opts['module']

    T = collections.namedtuple(typename, field_names, **opts)
    T.__new__.__defaults__ = (None,) * len(T._fields)
    if isinstance(default_values, collections.Mapping):
        prototype = T(**default_values)
    else:
        prototype = T(*default_values)
    T.__new__.__defaults__ = tuple(prototype)
    return T


# Example:
Friend = namedtuple_with_defaults('Friend','first_name last_name email_address favourite_module least_favourite_module',rename=True,verbose=True)
example1 = Friend(first_name='Guido', last_name='van Rossum', favourite_module='helpista', least_favourite_module=None)

print(example1)
# Output: Friend(first_name='Guido', last_name='van Rossum', email_address=None, favourite_module='helpista', least_favourite_module=None)

# Example 2
example2 = RubyFriend(first_name='Guido', last_name='van Rossum', favourite_module='Rails', least_favourite_module=None)

# Uh oh, an error!

Traceback (most recent call last):
# ... blah blah blah
TypeError: __new__() missing 1 required positional argument: 'email_address'