How can A.f defined in module A get list of function defined in B if A.f was called from B

Question

Let's say I have B.py

import A

def F():
    pass

def G():
    pass

if __name__ == '__main__':
    A.f()

And when I run it I would like A.f to output list of functions defined in B.py like this

./B.py
['F', 'G']

The question is what should I write in A.py?

def f():
    ???

It seems to be possible because doctest does something like this.

Update Thank you for your responses, but I forgot to mention one more restriction: I would not like to do import B in A.py.

Let me try to explain why: A.py is a library for runing MapReduce jobs. You just import A and run some A.f at the vary end of your script. Then A.f analizes what functions you defined and executes them on server. So A.f can not import every module it was called from.

Or can it? Can function know where it was called from?

Update

def f():
    module = sys.modules['__main__']
    functions = inspect.getmembers(module, inspect.isfunction)
    ...

possible duplicate of [Find functions explicitly defined in a module (python)](http://stackoverflow.com/questions/1106840/find-functions-explicitly-defined-in-a-module-python) — kennytm, May 01 '12 at 18:36

mgilson · Accepted Answer · 2012-05-02T00:31:32.540

3

def f():
    import B
    import inspect

    functions=inspect.getmembers(B,inspect.isfunction)

http://docs.python.org/library/inspect.html#inspect.getmembers

EDIT

I haven't tried it, but it seems like you could pass the module as an argument to f and use that.

def f(mod):
    import inspect
    functions=inspect.getmembers(mod,inspect.isfunction)
    return functions

Then, from B, you could do something like:

import sys
import A
myfuncs=A.f(sys.modules[__name__])

edited May 02 '12 at 00:31

answered May 01 '12 at 18:38

mgilson

300,191
65
633
696

@alexanderkuk I've posted an idea that *might* work for you, though I don't have the time to test it. – mgilson May 01 '12 at 19:29
@tapan Thanks. I'll remove the disclaimer. – mgilson May 02 '12 at 00:31

score 2 · Answer 2 · answered May 01 '12 at 18:36

2

This is actually pretty easy to do using the dir() function:

import B

def f():
    print(dir(B))

Which gives:

['A', 'F', 'G', '__builtins__', '__cached__', '__doc__', '__file__', '__name__', '__package__']

As you can see, this does include the hidden values that exist in the module that you normally don't see. If you want to be more specific about the things you want, check out the inspect module.

answered May 01 '12 at 18:36

Gareth Latty

86,389
17
178
183

You can't do circular imports. – Niklas B. May 01 '12 at 18:37
@NiklasB. You can - try running this. It works. I'm not saying it's a great practice, but it does work. – Gareth Latty May 01 '12 at 18:38
Really? I have to check, last time I needed something like this it wasn't possible. Disregard my comment if it is, of course. – Niklas B. May 01 '12 at 18:38
Indeed. I stand corrected. Maybe you should do `filter(callable, dir(B))`, though. – Niklas B. May 01 '12 at 18:39
2

@NiklasB. You can run into problems with circular imports, but it won't produce errors in all cases. – Gareth Latty May 01 '12 at 18:39
Yeah, last time it would work, but `B` would have no members inside `A`. Obviously this has changed since. – Niklas B. May 01 '12 at 18:40

How can A.f defined in module A get list of function defined in B if A.f was called from B

2 Answers2