Workaround for equality of nested functions

Question

I have a nested function that I'm using as a callback in pyglet:

def get_stop_function(stop_key):
    def stop_on_key(symbol, _):
        if symbol == getattr(pyglet.window.key, stop_key):
            pyglet.app.exit()
    return stop_on_key

pyglet.window.set_handler('on_key_press', get_stop_function('ENTER'))

But then I run into problems later when I need to reference the nested function again:

pyglet.window.remove_handler('on_key_press', get_stop_function('ENTER'))

This doesn't work because of the way python treats functions:

my_stop_function = get_stop_function('ENTER')
my_stop_function is get_stop_function('ENTER')  # False
my_stop_function == get_stop_function('ENTER')  # False

Thanks to two similar questions I understand what is going on but I'm not sure what the workaround is for my case. I'm looking through the pyglet source code and it looks like pyglet uses equality to find the handler to remove.

So my final question is: how can I override the inner function's __eq__ method (or some other dunder) so that identical nested functions will be equal?

(Another workaround would be to store a reference to the function myself, but that is duplicating pyglet's job, will get messy with many callbacks, and anyways I'm curious about this question!)

Edit: actually, in the questions I linked above, it's explained that methods have value equality but not reference equality. With nested functions, you don't even get value equality, which is all I need.

Edit2: I will probably accept Bi Rico's answer, but does anyone know why the following doesn't work:

def get_stop_function(stop_key):
    def stop_on_key(symbol, _):
        if symbol == getattr(pyglet.window.key, stop_key):
            pyglet.app.exit()
    stop_on_key.__name__ = '__stop_on_' + stop_key + '__'
    stop_on_key.__eq__ = lambda x: x.__name__ == '__stop_on_' + stop_key + '__'
    return stop_on_key

get_stop_function('ENTER') == get_stop_function('ENTER')  # False
get_stop_function('ENTER').__eq__(get_stop_function('ENTER'))  # True

Answer 1

You could create a class for your stop functions and define your own comparison method.

class StopFunction(object):

    def __init__(self, stop_key):
        self.stop_key = stop_key

    def __call__(self, symbol, _):
        if symbol == getattr(pyglet.window.key, self.stop_key):
            pyglet.app.exit()

    def __eq__(self, other):
        try:
            return self.stop_key == other.stop_key
        except AttributeError:
            return False

StopFunciton('ENTER') == StopFunciton('ENTER')
# True
StopFunciton('ENTER') == StopFunciton('FOO')
# False