[Python-Dev] PEP 396, Module Version Numbers

[Barry Warsaw]

On Apr 07, 2011, at 04:53 PM, Nick Coghlan wrote:

>What I would like to see the PEP say is that if you don't *have* a
>setup.cfg file, then go ahead and embed the version directly in your
>Python source file. If you *do* have one, then put the version there
>and retrieve it with "pkgutil" if you want to provide a __version__
>attribute.

I'm not convinced there's consensus on that, i.e. that the version string
should go in setup.cfg if it exists.  It doesn't help that the pkgutil API for
doing that is pretty ugly.

>Barry is welcome to make a feature request to allow that dependency to
>go the other way, with the packaging system reading the version number
>out of the source file, but such a suggestion doesn't belong in an
>Informational PEP. If such a feature is ever accepted, then the
>recommendation in the PEP could be updated.

Note that there's really no reason why packaging has to grow a method to do
this.  It would be a convenience, but not a requirement.  For example, I have
my own helper function (something like the now elided get_version() code) that
digs version strings out of files for my own packages just fine.  True, it
doesn't handle the full normalized version specification, but I don't care
because my version numbers will never look that complex.  If yours does, and
you don't want to rely on the pkgutil API, or you need it to work even when
your module isn't installed, well, write your own code!

The Deriving section of the PEP is not the most important part of it, and is
not making specific recommendations.  If it's not clear that it's only
providing examples, or it's distracting, then maybe it's better off being
removed, cut down or rewritten.

Cheers,
-Barry
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