[Distutils] why does pkg_resources call imp.load_module?
pje at telecommunity.com
Thu Feb 19 16:31:30 CET 2009
At 02:06 PM 2/19/2009 +0000, Karsten Petersen wrote:
>I'm trying to make Google App Engine work smoothly with setuptools
>and I'm struggling to understand one specific piece of what
>pkg_resources does. Would you mind giving me a hint?
>The question is basically: Why does _handle_ns() in pkg_resources
>import other modules that implement the same namespace. It's not
>using the module handle that is returned. I looked for side effects
>but the only ones I found was that exceptions are raised if the
>other modules are broken and that the modules __file__ var is
>changed to point to the last found module that implements the
>namespace in question.
>What am I missing?
In the unlikely event that one of the __init__.py's contains anything
other than namespace setup code, loading the module ensures that it
will be run. This was done for compatibility with older packages
that use distutils hacks to create a namespace package. (i.e.,
shipping one package with the __init__.py, and the rest without
it). Such packages need to have their __init__.py code run.
It probably won't hurt anything too badly to leave it out, since it's
strictly for compatibility with a configuration that's deprecated
anyway. (At least, it's deprecated for setuptools.)
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