[Distutils] [proposal] version-free + lookup-friendly dist-info location

[Freddy Rietdijk]

Users may want to split installations over multiple folders and creating a
working environment by merging them (through symlinks / PYTHONPATH /
sys.path / site / .pth). Python doesn't support multiple versions of the
same module during runtime, and therefore I don't see any benefit in
including a "unique" identifier like the version number (which in fact
isn't unique, because one could also have multiple instances of the same
version but e.g. build differently).

In any case, forbidding installation of different versions in different
directories is not possible because, as I mentioned, one can create an
environment by simply merging site-packages folders.

On Fri, Mar 17, 2017 at 1:50 PM, Leonardo Rochael Almeida <
leorochael at gmail.com> wrote:

>
>
> On 17 March 2017 at 07:32, Paul Moore <p.f.moore at gmail.com> wrote:
>
>> On 17 March 2017 at 09:58, Ronny Pfannschmidt <opensource@
>> ronnypfannschmidt.de> wrote:
>> > [...]
>> > in order to address that i'd like to propose to switch
>> >
>> > from "{distribution}-{version}.dist-info/" to
>> "{distribution}.dist-info/"
>> >
>> > given that it has been used since quite a while i would prefer a quick
>> > feedback loop from the ML before thinking about writing a PEP.
>>
>> +1 from me. And maybe explicitly state that installing multiple
>> versions of a distribution is not supported. Although this opens a
>> somewhat larger can of worms, in that you can install different
>> versions in separate directories - say in system and user
>> site-packages - and that has subtle issues but is technically not
>> rejected at the moment.
>
>
> People today rely on being able to install different versions of packages
> already installed in other directories. System, vs User site-packages, as
> you mentioned is one example.
>
> The `--system-site-packages` switch to `virtualenv` is another. In my
> experience, many projects rely on pre-packaged hard-to-build system
> packages, while using virtualenv to install more up-to-date versions
> project dependencies.
>
> So maybe restrict it to stating that
>> installing multiple versions of a distribution *in the same directory*
>> is not supported and duck the bigger issue for now.
>>
>
> This is already the case everywhere. Even setuptools' `easy_install`,
> while capable of installing multiple versions of the same project in the
> same site-packages directory, is in reality installing each one to it's own
> `.egg` directory inside `site-packages` and can keep only one of
> them "active" at a time. ("active" meaning: importable without an explicit
> incantation to request a different installed version).
>
> I'm +0 on this proposal (the lack of enthusiasm coming from the fact that
> multiple projects will be affected), but I'm -lots on any proposal
> forbidding installation of different versions in different directories.
>
> Cheers,
>
> Leo
>
> _______________________________________________
> Distutils-SIG maillist  -  Distutils-SIG at python.org
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>
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