The python CLI always sets the __file__ variable, whether run as: $ python foobar.py or $ python -m foobar or $ python >>> import foobar # __file__ set in foobar module The idle program sets the __file__ variable properly when you do the import from the idle shell, but __file__ is not set with the "Run Module" (F5) command from the editor. I've included a patch file to set __file__, but it doesn't del it after the module has run. But maybe this is OK, because the os.chdir is not undone either???
I believe IDLE runs modules via execfile(), so I would expect the behavior to be similar, and execfile() does not set __file__. Doing "Run Module" is also IMO equivalent to doing execfile(), so this behavior retains consistency. However, I would expect __file__ to be set when running IDLE -r
