How can I hook a function in a python module?

Question

I have a package in my virtual environment installed in the site-packages folder of it. In that package there is a module with a bunch of functions. I want to change one of these functions without touching the package code, so I want to make a hook of that module and then change/overwrite the function so it behaves in the way I want.

I don't know if this is even possible in Python (I'm new to the language).

Example:

I have a package called their_package in my site-packages folder, inside I have a module named whatever.py with the following code:

import sys
import os
def this_is_a_function(parameter):
 //whatever logic in here
 return result

What I want is to hook the whatever.py module so I can redefine the this_is_a_function to have a different logic. Is this possible? I would appreciate a lot a code sample!

• Roman Bodnarchuk: How do you plan to use that hooked module later? Do you want to hook it only for one scenario (piece of logic), or for the whole Python interpreter session?
• Manuel Canga: Yes, there is a lbrary called wphooks for this purpose

Answer 1

You can redefine your function with:

import whatever
def this_is_a_function(parameter):
 pass
whatever.this_is_a_function = this_is_a_function

• Denis Bitouzé: I don't understand where is "redefined the this_is_a_function to have a different logic" as asked by the OP.
• tripleee: @DenisBitouzé It runs pass instead of whatever the function did before. Obviously replace this with something more complex if that's what you want.