How to create a copy of a python function [duplicate]

Answer 1

In Python3:

import types
import functools

def copy_func(f):
    """Based on http://stackoverflow.com/a/6528148/190597 (Glenn Maynard)"""
    g = types.FunctionType(f.__code__, f.__globals__, name=f.__name__,
                           argdefs=f.__defaults__,
                           closure=f.__closure__)
    g = functools.update_wrapper(g, f)
    g.__kwdefaults__ = f.__kwdefaults__
    return g

def f(arg1, arg2, arg3, kwarg1="FOO", *args, kwarg2="BAR", kwarg3="BAZ"):
    return (arg1, arg2, arg3, args, kwarg1, kwarg2, kwarg3)
f.cache = [1,2,3]
g = copy_func(f)

print(f(1,2,3,4,5))
print(g(1,2,3,4,5))
print(g.cache)
assert f is not g

yields

(1, 2, 3, (5,), 4, 'BAR', 'BAZ')
(1, 2, 3, (5,), 4, 'BAR', 'BAZ')
[1, 2, 3]

---

In Python2:

import types
import functools
def copy_func(f):
    """Based on http://stackoverflow.com/a/6528148/190597 (Glenn Maynard)"""
    g = types.FunctionType(f.func_code, f.func_globals, name=f.func_name,
                           argdefs=f.func_defaults,
                           closure=f.func_closure)
    g = functools.update_wrapper(g, f)
    return g

def f(x, y=2):
    return x,y
f.cache = [1,2,3]
g = copy_func(f)

print(f(1))
print(g(1))
print(g.cache)
assert f is not g

yields

(1, 2)
(1, 2)
[1, 2, 3]