[Distutils] PEP 517: Build system API

Daniel Holth dholth at gmail.com
Mon Nov 28 13:23:42 EST 2016


Here is the design. The build tool provides the install tool with a
directory, or if you want to get fancy, a list of directories, that should
be added to PYTHONPATH. The build tool builds into that path. The install
tool makes sure Python can find it. This will make anyone who uses
setuptools happy.

So PEP 517 does not need an editable install hook to support editable
installs. It can just expose the equivalent of setuptools'
package_dir={'':'src'}, and include a 'build in place' hook, and the
feature is preserved.

In this way setuptools users can be happy, and only users of build systems
that can't work this way are waiting for a more complicated design.

On Mon, Nov 28, 2016 at 1:01 PM Paul Moore <p.f.moore at gmail.com> wrote:

> On 28 November 2016 at 17:53, Chris Barker <chris.barker at noaa.gov> wrote:
> >> Why not just have a single pth file, maintained by the build
> >> tool, for all editable installs?
> >
> > shouldn't that be maintained by the install tool? i.e. pip -- the whole
> idea
> > is that the install tool is different than the built tool, yes? and
> adding a
> > package in editable mode is an installation job, not a build job.
> >
> > Also -- the idea here is that pip will know it's installed so it can
> > upgrade, de-install, etc, so it really is pip's job to maintain the
> > "editable_install.pth" file.
>
> Sorry - I was confusing "build tool" vs "install tool" here. Not
> intentionally, but the confusion is real. Setuptools is a build tool,
> and yet (currently) handles editable installs. So IMO, part of
> finalising editable install support would be thrashing out which
> aspects of the process are the responsibility of the build tool, and
> which the install tool. That's a non-trivial design job, so in the
> interests of keeping things moving, it seems to me that "defer a
> decision for now" remains the right decision here. Not to claim that
> editable installs aren't important, simply to avoid having all of the
> rest of the proposal stalled while we sort out the editable design.
>
> Paul
>
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