Extension methods in Python

Does Python have extension methods like C#? Is it possible to call a method like:

MyRandomMethod()

on existing types like int?

myInt.MyRandomMethod()

You can add whatever methods you like on class objects defined in Python code (AKA monkey patching):

>>> class A(object):
>>>     pass


>>> def stuff(self):
>>>     print self

>>> A.test = stuff
>>> A().test()

This does not work on builtin types, because their __dict__ is not writable (it's a dictproxy).

So no, there is no "real" extension method mechanism in Python.


not sure if that what you're asking but you can extend existing types and then call whatever you like on the new thing:

class  int(int):
     def random_method(self):
           return 4                     # guaranteed to be random
v = int(5)                              # you'll have to instantiate all you variables like this
v.random_method()

class int(int):
    def xkcd(self):
        import antigravity
        print(42)

>>>v.xkcd()
Traceback (most recent call last):
  File "<pyshell#81>", line 1, in <module>
    v.xkcd()
AttributeError: 'int' object has no attribute 'xkcd'
c = int(1)
>>> c.random_method()
4
>>> c.xkcd()
42

hope that clarifies your question


It can be done with Forbidden Fruit (https://pypi.python.org/pypi/forbiddenfruit)

Install forbiddenfruit:

pip install forbiddenfruit

Then you can extend built-in types:

>>> from forbiddenfruit import curse

>>> def percent(self, delta):
...     return self * (1 + delta / 100)

>>> curse(float, 'percent', percent)
>>> 1.0.percent(5)
1.05

Forbidden Fruit is fundamentally dependent on the C API, it works only on cpython implementations and won’t work on other python implementations, such as Jython, pypy, etc.