@mixedmethod mixes class- and instance- method into one.

#!/usr/bin/env python
# -*-coding: utf8-*-
# Compatibility: python 2 and py3k
# Title: mixedmethod.py
# Author: Gribouillis
# Created: 2012-01-13 12:10:17.722112 (isoformat date)
# License: Public Domain
# Use this code freely.

from __future__ import print_function
from functools import partial
import sys

"""This module implements a mixedmethod() decorator for class definitions.
"""

version_info = (0, 1)
version = ".".join(map(str, version_info))


class mixedmethod(object):
    """This decorator mutates a function defined in a class into a 'mixed' class and instance method.
    
    Usage:
    
        class Spam:
        
            @mixedmethod
            def egg(self, cls, *args, **kwargs):
                if self is None:
                    pass # executed if egg was called as a class method (eg. Spam.egg())
                else:
                    pass # executed if egg was called as an instance method (eg. instance.egg())

    The decorated methods need 2 implicit arguments: self and cls, the former being None when
    there is no instance in the call. This follows the same rule as __get__ methods in python's
    descriptor protocol.
    """
    def __init__(self, func):
        self.func = func
    def __get__(self, instance, cls):
        return partial(self.func, instance, cls)

if __name__ == '__main__':
    
    class Spam(object):
        
        @mixedmethod
        def ham(self, cls, *args):
            if self is None:
                print("Spam.ham() was called as a class method with {0}.".format((self, cls)+ args))
            else:
                print("Spam.ham() was called as an instance method with {0}.".format((self, cls) + args))
            
        def __repr__(self):
            return '<Spam instance>'

    egg = Spam()
    egg.ham(5)
    Spam.ham(5)

    """ my output -->
Spam.ham() was called as an instance method with (<Spam instance>, <class '__main__.Spam'>, 5).
Spam.ham() was called as a class method with (None, <class '__main__.Spam'>, 5).
    """