How do I access a main frunction from an import module?

Carl Banks pavlovevidence at gmail.com
Fri Nov 24 15:39:54 CET 2006


Jim wrote:
> I have created an import module.  And would like to access a function
> from the main script, e.g.,
>
> file abc.py:
> ###################
> def a():
>     m()
>     return None
> ####################
>
> file main.py:
> #####################
> from abc import *
> def m():
>     print 'something'
>     return None
>
> a()
> ######################


You can do it with "from __main__ import m" atop abc.py (the module
invoked at the command line is always called __main__).

However, I *highly* suggest you put m in another file.  Importing
variables from __main__ would make your program incompatible with many
useful tools.  For example, if you invoke the Python profiler on your
code, like this:

    python -m profile main.py

it will break your code, because __main__ no longer refers to main.py
but to profile.py (from the Python library).  Importing from __main__
adversely affects tools such as PyChecker and PyLint.

The exception to this would be if abc.py is specifically designed as a
utility for interactive use; then it would be ok and useful.


Carl Banks




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