Use a class in the context of a different module

Question

I want to modify some classes in the standard library to use a different set of globals the ones that other classes in that module use.

Example

This exampl

Answer 1

You can't change the globals without affecting all other users of the module, but what you sort of can do is create a private copy of the whole module.

I trust you are familiar with sys.modules, and that if you remove a module from there, Python forgets it was imported, but old objects referencing it will continue to do so. When imported again, a new copy of the module will be made.

A hacky solution to your problem could would be something like this:

import sys
import threading

# Remove the original module, but keep it around
main_threading = sys.modules.pop('threading')

# Get a private copy of the module
import threading as private_threading

# Cover up evidence by restoring the original
sys.modules['threading'] = main_threading

# Modify the private copy
private_threading._allocate_lock = my_allocate_lock()

And now, private_threading.Lock has globals entirely separate from threading.Lock!

Needless to say, the module wasn't written with this in mind, and especially with a system module such as threading you might run into problems. For example, threading._active is supposed to contain all running threads, but with this solution, neither _active will have them all. The code may also eat your socks and set your house on fire, etc. Test rigorously.