The commonest example is that distribute provides setuptools. Daniel Holth
On Nov 12, 2012, at 6:10 PM, Vinay Sajip <[email protected]> wrote: > PJ Eby <pje <at> telecommunity.com> writes: > >> Test dependencies allow you to depend on a test framework (e.g. nose) without >> requiring it to be installed at runtime. Setup dependencies let you depend >> on tools like Pyrex or Cython in order to compile a binary package, without >> requiring them to be available at runtime. > > Oh, I understand why the distinctions exist, and they seem reasonable to me. > Sorry I wasn't clear - I meant that I wasn't sure how widely these were used. > I > made the comment because I thought that the distinction wasn't preserved in > the > new metadata format, but I must have misread - Daniel commented that the > distinction *is* preserved. > >> Pkg_resources uses a "greedy" dependency resolver, so it ignores >> circularity as a side-effect. That is, as soon as the first requirement for >> [explanation snipped] > > Thanks for the explanation. It seems to me that the new metadata formats make > dependency resolution more difficult because they allow for e.g. > 'Provides-Dist' as a multi-value field. Perhaps I'm misunderstanding, but > this, > it seems to me, opens the door for a project named A on PyPI to provide e.g. > "A (1.0)", "B (1.5)" and "C (2.0)", and likewise, projects B and C on PyPI > could provide slightly different versions of "A", "B" and "C". You can soon > get > a rat's nest of dependencies in the resolver - and if you get something like > the case that Carl linked to, where some element of backtracking might be in > order, it doesn't seem computationally straightforward to resolve > dependencies, > perhaps even with a SAT solver in the mix. Is this a case of practicality > losing out to purity? Assuming it's easy to pull any version from an index, I > can't see a compelling case for any distribution archive for A to ever provide > anything other than e.g. "A (x.y)". Can someone point me to the real need for > multi-valued "Provides" fields? Or have I completely misunderstood this aspect > of the metadata? > > Regards, > > Vinay Sajip > > _______________________________________________ > Distutils-SIG maillist - [email protected] > http://mail.python.org/mailman/listinfo/distutils-sig _______________________________________________ Distutils-SIG maillist - [email protected] http://mail.python.org/mailman/listinfo/distutils-sig
