Proxy object in Python

Question

I\'m looking for way to pass method calls through from an object (wrapper) to a member variable of an object (wrappee). There are potentially many methods that need to be ex

Answer 1

Here's another monkey-patch method. This one copies methods into the Wrapper class directly rather than the created wrapper object. The key advantage to this one is that all special methods such as __add__ will work.

class Wrapper(object):
    def __init__(self, wrappee):
        self.wrappee = wrappee

    def foo(self):
        print('foo')


def proxy_wrap(attr):
    "This method creates a proxy method that calls the wrappee's method."
    def f(self, *args):
        return getattr(self.wrappee, attr)(*args)
    return f

# Don't overwrite any attributes already present
EXCLUDE = set(dir(Wrapper))

# Watch out for this one...
EXCLUDE.add('__class__')

for (attr, value) in inspect.getmembers(Wrappee, callable):
    if attr not in EXCLUDE:
        setattr(Wrapper, attr, proxy_wrap(attr))

I used this to wrap numpy arrays. With Wrappee set to np.ndarray:

import numpy as np

Wrappee = np.ndarray

# [The block I wrote above]

wrapped = Wrapper(np.arange(10))

Operations such as wrapped + 1 still work.