[Catalog-sig] "python 2 only" classifier

[martin at v.loewis.de]

>> The use of trove classifiers at all isn't compulsory on PyPI, so although
>> I agree it would be *preferable* for all authors to use them correctly I
>> don't think PyPI is going to require it any time soon.
>>
>>
>>
> Are we happy that it isn't compulsory? I mean, there are a lot of
> compulsory lines in setup.py/cfg, why not require a compatibility tag?

Packages on PyPI don't even need to use setup.py at all, and may use
autoconf or plain make instead.

There is always a conflict of interest wrt. PyPI between package authors
and package users. Package users often demand that package authors do
something, and then ask that PyPI enforces this. Package authors then explain
reasons why they don't want to do that, and threaten to host their packages
elsewhere.

In the specific case, I don't think that requiring version classifiers would
be useful. First, tools (like setuptools) might start filling out "default"
values for these, so that users don't have to modify their setuo.pys.
Furthermore, proper declaration wouldn't have helped you either: if the
2.7 classifier is missing, is it because the software doesn't work on 2.7,
or is it that the author hasn't added 2.7 to the list?

Regards,
Martin