Question

I would like to get a reference back to the function that created an iterator. In my case I am interested in getting the original docstring.

Example:

def my_generator():
    """this is my generator"""
    for x in (1,2,3):
        yield x


my_iter = my_generator()

# in another part of my code where I Only have access to the iterator
# no access to the generator function "my_generator"
assert my_iter.????.__doc__ == "this is my generator"

Answer 1

It feels hacky, but one way would to get at the docstring would be via co_consts:

localhost-2:coding $ cat mod1.py
def my_generator():
    """this is my generator"""
    for x in (1,2,3):
        yield x

it = my_generator()

localhost-2:coding $ python
Python 2.7.2 (v2.7.2:8527427914a2, Jun 11 2011, 15:22:34) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import mod1
>>> mod1.it.__doc__
>>> mod1.it.gi_code.co_consts[0]
'this is my generator'
>>> z = mod1.my_generator()
>>> z.__doc__
>>> z.gi_code.co_consts[0]
'this is my generator'

I’d be more inclined to figure out some decorator to apply to a generator function to make sure the docstring stays.

If you need the function itself, how about:

>>> import mod1
>>> z = mod1.my_generator()
>>> z.__doc__
>>> z.gi_frame.f_globals[z.__name__]
<function my_generator at 0x1004b7cf8>
>>> z.gi_frame.f_globals[z.__name__] is mod1.my_generator
True
>>> z.gi_frame.f_globals[z.__name__].__doc__
'this is my generator'

but I make no promises that this works for every case..