How do you implement __str__ for a function?

Question

Given a function foo:

def foo(x):
     pass

Printing its representation by invoking str or repr give

Answer 1

If you find yourself wrapping functions, it's useful to look at functools.partial. It's primarily for binding arguments of course, but that's optional. It's also a class that wraps functions, removing the boilerplate of doing so from scratch.

from functools import partial

class foo(partial):
    def __str__(self):
        return "I'm foo!"

@foo
def foo():
    pass

assert foo() is None
assert str(foo) == "I'm foo!"