Enable install through pyproject.toml

[matthewfeickert]

Description

Given PEP 518 it would be nice to have the ability to install pyhf through the pyproject.toml (which already exists since PR #322) as an alternative (...or in the future a replacement) to using the setup.py with pip. This would also allow installation with dependency managers like Poetry.

[matthewfeickert]

Should also consider moving the bulk of setup.py to setup.cfg to take advantage of setuptools's work to support PEP 517.

c.f. Bernat Gabor's post on this

[webknjaz]

Just drop in a pyproject.toml like this and that's it:

[build-system]
requires = [
  "setuptools >= 41.0.0",
  "setuptools_scm >= 1.15.0",
  "setuptools_scm_git_archive >= 1.0",
  "wheel",
]
build-backend = "setuptools.build_meta"

[matthewfeickert]

Given PR #455 this Twitter thread from @bskinn will probably be useful in the future for doing this properly.

[webknjaz]

This mostly hit tox users (because it always uses the latest published pip): tox-dev/tox#1276. But the maintainers are quite responsive and the fix should be out soon anyway :)

[matthewfeickert]

This mostly hit tox users

Yeah, it happened to us as well (PR #455). I've been watching the Issue, which should help in the future.

[webknjaz]

It's not the same: tox updates pip to the latest version and the workaround to this is quite non-trivial for tox specifically :)

[bskinn]

Huh. It must be a particular style of tox usage, because my tox works fine for two different projects, using it for factorial testing of dependency matrices.

[webknjaz]

You'll hit the bug only if you have a combo of pyproject.toml file existing in the project + editable mode.

[webknjaz]

The workaround, for now, is smth like this: ansible/molecule#2009

[bskinn]

Interesting... what's the use case for an editable install inside a tox environment? Post-install inspection/meddling?

[webknjaz]

Just for development purposes. By default, tox doesn't reinstall the env. Unless you make it.
And use_develop = True is it's default setting.
This way, when you rerun tests they are executed against existing env + your source code is already linked there. Of course, this assumes you don't have something that has to be compiled every time.