On May 29, 2017, at 3:05 AM, Nathaniel Smith <njs@pobox.com> wrote:

I think there's some pip bug somewhere discussing this, where Ralf
Gommers and I point out that this is a complete showstopper for
projects with complex and expensive builds (like scipy). If 'pip
install .' is going to replace 'setup.py install', then it needs to
support incremental builds, and the way
setup.py-and-almost-every-other-build-tool do this currently is by
reusing the working directory across builds.

Wouldn’t supporting incremental builds the way ccache does work just fine? Have a per build tool cache directory somewhere that stores cached build output for each individual file keyed off a hash or something? (For that matter, if someone wants incremental rebuilds, couldn’t they just *use* ccache as their CC?).