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