On 30 October 2015 at 11:50, Robert Collins <robe...@robertcollins.net> wrote: ... > However, the big step you're proposing that I think is fundamentally > unsound is that of requiring a wheel be built before dependencies can > be queried. Wheels are *expensive* to build in enough cases that I > really believe we have a choice between being able to fix issue 988 or > utilising wheels as the interface to get at install metadata. Remember > too that the numpy ABI discussion is going to cause install > dependencies to depend on the version of numpy present at build-time, > so the resolver is going to have to re-evaluate the dependencies for > those distributions when it selects a new numpy version: so its not > even a one-time-per-package cost, its a > one-time-per-arc-of-the-N!-graph-paths cost.
On further thought there is one mitigating factor here - we'd have to be building numpy fully anyway for the cases where numpy is a build-dependency for things further up the stack, so even in my most paranoid world we will *anyway* have to pay that cost - but we can avoid the cost of multiple full rebuilds of C extensions built on top of numpy. I think avoiding that cost is still worth it, its just a little more into the grey area rather than being absolutely obviously worth it. -Rob -- Robert Collins <rbtcoll...@hp.com> Distinguished Technologist HP Converged Cloud _______________________________________________ Distutils-SIG maillist - Distutils-SIG@python.org https://mail.python.org/mailman/listinfo/distutils-sig
