What happened to module.__file__?

[Steven D'Aprano]

I've just started using a Debian system, instead of the usual RedHat
based systems I'm used to, and module.__file__ appears to have
disappeared for some (but not all) modules.

On Fedora:

[steve@orac ~]$ python -E
Python 2.6.2 (r262:71600, Aug 21 2009, 12:22:21)
[GCC 4.4.1 20090818 (Red Hat 4.4.1-6)] on linux2
Type "help", "copyright", "credits" or "license" for more information.'/usr/lib/python2.6/lib-dynload/mathmodule.so'



and on Debian squeeze:

steve@runes:~$ python -E
Python 2.6.6 (r266:84292, Dec 27 2010, 00:02:40)
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute '__file__'


What's going on?

 

[MRAB]

I've just started using a Debian system, instead of the usual RedHat
based systems I'm used to, and module.__file__ appears to have
disappeared for some (but not all) modules.

On Fedora:

[steve@orac ~]$ python -E
Python 2.6.2 (r262:71600, Aug 21 2009, 12:22:21)
[GCC 4.4.1 20090818 (Red Hat 4.4.1-6)] on linux2
Type "help", "copyright", "credits" or "license" for more information.'/usr/lib/python2.6/lib-dynload/mathmodule.so'



and on Debian squeeze:

steve@runes:~$ python -E
Python 2.6.6 (r266:84292, Dec 27 2010, 00:02:40)
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.Traceback (most recent call last):
File "<stdin>", line 1, in<module>
AttributeError: 'module' object has no attribute '__file__'


What's going on?

The documentation for __file__ says: """The __file__ attribute is not
present for C modules that are statically linked into the interpreter;
for extension modules loaded dynamically from a shared library, it is
the pathname of the shared library file."""

Interestingly, none of the versions on Windows that I've tried have
that attribute for the math module. Is it platform-dependent?

 

[Robert Kern]

I've just started using a Debian system, instead of the usual RedHat
based systems I'm used to, and module.__file__ appears to have
disappeared for some (but not all) modules.

On Fedora:

[steve@orac ~]$ python -E
Python 2.6.2 (r262:71600, Aug 21 2009, 12:22:21)
[GCC 4.4.1 20090818 (Red Hat 4.4.1-6)] on linux2
Type "help", "copyright", "credits" or "license" for more information.

import math
math.__file__

'/usr/lib/python2.6/lib-dynload/mathmodule.so'



and on Debian squeeze:

steve@runes:~$ python -E
Python 2.6.6 (r266:84292, Dec 27 2010, 00:02:40)
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.

import math
math.__file__

Traceback (most recent call last):
File "<stdin>", line 1, in<module>
AttributeError: 'module' object has no attribute '__file__'


What's going on?

The documentation for __file__ says: """The __file__ attribute is not
present for C modules that are statically linked into the interpreter;
for extension modules loaded dynamically from a shared library, it is
the pathname of the shared library file."""

Interestingly, none of the versions on Windows that I've tried have
that attribute for the math module. Is it platform-dependent?

It is build-dependent. Windows builds typically have math and several other
stdlib "extension" modules built into the PythonXY.dll . Unix builds typically,
but apparently not always, leave mathmodule.so and others as separate extension
modules.

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco