An way to add methods to an instance in Python

gistfile1.py

'''
An way to add methods to an instance.

>>> class Person(object):
...     def __init__(self, name):
...         self.name = name
...
>>> def upper_name(self):
...     return self.name.upper()
...

>>> p = Person("Bob")
>>> p.name
'Bob'

# trying just add the function to an instance won't work if you plan to 
# use ``self``

>>> p.upper_name = upper_name
>>> p.upper_name()
Traceback (most recent call last):
...
TypeError: upper_name() takes exactly 1 argument (0 given)

>>> add_instance_method(upper_name, p)
>>> p.upper_name()
'BOB'

'''

import types

def add_instance_method(function, instance):
    method = types.MethodType(function, instance, instance.__class__)
    setattr(instance, function.func_name, method)


if __name__ == '__main__':
    import doctest
    print doctest.testmod()