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[Python-Dev] Safely importing zip files with C extensions

Thomas Heller theller at ctypes.org
Thu Mar 28 15:44:08 CET 2013 
Am 27.03.2013 20:38, schrieb Vinay Sajip:
>> This quote is here to stop GMane complaining that I'm top-posting. Ignore.
>
> I've already posted this to distutils-sig, but thought that it might be of
> interest to readers here as it relates to importing C extensions ...
>
> zipimport is great, but there can be issues importing software that contains
> C extensions. But the new wheel format (PEP 427) may give us a better way of
> importing zip files containing C extensions. Since wheels are .zip files, they
> can sometimes be used to provide functionality without needing to be installed.
> But whereas .zip files contain no convention for indicating compatibility with
> a particular Python, wheels do contain this compatibility information. Thus, it
> is possible to check if a wheel can be directly imported from, and the wheel
> support in distlib allows you to take advantage of this using the mount() and
> unmount() methods. When you mount a wheel, its absolute path name is added to
> sys.path, allowing the Python code in it to be imported. (A DistlibException is
> raised if the wheel isn't compatible with the Python which calls the mount()
> method.)

The zip-file itself could support importing compiled extensions when it 
contains a python-wrapper module that unpacks the .so/.dll file 
somewhere, and finally calls imp.load_dynamic() to import it and replace 
itself.

Thomas
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