[Distutils] Pep 440 question/clarification Version specifiers no "Or" available

[Robert Collins]

On 9 September 2016 at 15:10, Nick Coghlan <ncoghlan at gmail.com> wrote:
> On 9 Sep 2016 12:32 pm, "Robert Collins" <robertc at robertcollins.net> wrote:

>> tl;dr the ramifications of OR are much deeper than those of AND for
>> this problem space, and we don't even have AND solved properly - Issue
>> 988.
>
> Disjoint environment markers provide most of the capabilities we actually
> need (like installing one dependency on Py2 and a different one on Py3)
> without ever forcing the resolver to make an arbitrary choice between them.

Yup :) and we've got that pretty solidly adoptable now - chunk of work
that it was ;).

> There are currently some bugs even in that, though - installing an sdist or
> wheel directly instead of via a requirements file bypasses the environment
> marker checks for its direct dependencies :(
>
> (Steve Kowalik was trying to figure that one out at the PyCon AU sprints,
> but I don't believe he was able to track down where the missing check should
> go)

I didn't mention it before but I should - its my view we should be
really conservative about an OR in the dependency language, for the
reasons in my earlier email.

-Rob