[docs] [issue12920] Document that inspect.getsource only works for objects loaded from files, not interactive session

[Éric Araujo]

Éric Araujo added the comment:

> It seems to work perfectly on command line though.

If the code is saved in a file, yes, but not in an interactive interpreter.  This is not actually related to IDLE, but to the fact that inspect.getsource merely finds the __file__ attribute of the module object for its argument.  If a module object has no file, the error message indicates that it’s a built-in module (like sys), but this fails to take into account the special __main__ module in an interactive interpreter.

It might be worth it to improve the error message, and in any case the documentation can be improved.

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stage:  -> needs patch
title: inspect.getsource fails to get source of local classes -> Document that inspect.getsource only works for objects loaded from files, not interactive session
versions: +Python 3.4

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue12920>
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