On Tuesday, February 19, 2013 at 3:25 PM, Paul Moore wrote: > On 19 February 2013 13:40, Nick Coghlan <ncogh...@gmail.com > (mailto:ncogh...@gmail.com)> wrote: > > > If a tools wants to support metadata 2.0, it has to support all > > > the complicated stuff as well, i.e. handle the requires fields, > > > the environment markers and version comparisons/sorting. > > > > > > > > > Which is what distutils2 can be used for now, and what distlib will > > provide without the unwanted build system infrastructure in > > distutils2. > > > > > One particular item in Metadata 2.0 which needs to be addressed is > requirements specifiers, as used in (for example) Requires-Dist. These > take forms like "DistName (>= ver)". There are a number of potential > issues here: > > 1. This differs from the pkg_resources format (which omits the > parentheses). Having 2 subtly different formats is not a good idea in > the long term. At the moment, pkg_resources format is used in pip > requirements (on the command line and in requirement files) as well as > in setuptools/distribute and possibly elsewhere. > 2. There is currently no code that I am aware of that implements this > spec. I don't believe distlib does (yet - give Vinay 5 minutes and who > knows? :-)), pkg_resources as I said implements a different format, > and distutils2, apart from being a big dependency to cover just this > point, only matches the version (not the project name) and presumably > does so using the distutils2 version ordering (which is incompatible > with Metadata 2.0). > >
It should be alongside the version stuff, atleast it was in distutils2. > 3. The format is fiddly to parse and process - nobody is likely to > implement it for themselves without a library that does it (especially > not when using pkg_resources is so easy). > > The PEP needs a rationale as to why the pkg_resources format wasn't > used, and should suggest a migration path for projects which currently > use the pkg_resources style (such as pip's requirements files). > > Paul > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org (mailto:Python-Dev@python.org) > http://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > http://mail.python.org/mailman/options/python-dev/donald.stufft%40gmail.com > >
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