Getting callable object from the frame

Question

Given the frame object (as returned by sys._getframe, for instance), can I get the underlying callable object?

Code explanation:

def foo():
    frame = s         


        

Answer 1

To support all cases, including the function being part of a class or just a global function, there is no straight-forward way of doing this. You might be able to get the complete call stack and iterate your way down through globals(), but it wouldn't be nice...

The closest I can get you is this:

import sys, types

def magic():
    # Get the frame before the current one (i.e. frame of caller)
    frame = sys._getframe(1)
    # Default values and closure is lost here (because they belong to the
    # function object.)
    return types.FunctionType(frame.f_code, frame.f_globals)

class MyClass(object):
    def foo(self, bar='Hello World!'):
        print bar
        return magic()

test = MyClass()

new_foo = test.foo()
new_foo(test, 'Good Bye World!')

You'll be executing the exact same code, but it'll be in a new code wrapper (e.g., FunctionType.)

I suspect you want to be able to restore the state of your application based on a stack... Here's something that will at least call the functions as similarly as possible to the original calls (the closure is still left out, because if you could get closures from the frames, getting the function that was called would be pretty easy):

import sys, types

class MyClass(object):
    def __init__(self, temp):
        self.temp = temp

    def foo(self, bar):
        print self.temp, bar
        return sys._getframe()

def test(hello):
    print hello, 'World!'
    return sys._getframe()

def recall(frame):
    code = frame.f_code
    fn = types.FunctionType(
        code, frame.f_globals, code.co_name,
        # This is one BIG assumption that arguments are always last.
        tuple(frame.f_locals.values()[-code.co_argcount:]))
    return fn()


test1 = MyClass('test1')
frame1 = test1.foo('Hello World!')

test2 = MyClass('test2')
frame2 = test2.foo('Good Bye World!')
frame3 = test2.foo('Sayonara!')

frame4 = test('HI')

print '-'

recall(frame4)
recall(frame3)
recall(frame2)
recall(frame1)