Makes `compile` and `sync` directly runnable as modules

[jamesbraza]

Before:

> python -m piptools.scripts.compile --help

After:

> python -m piptools.scripts.compile --help
Usage: python -m piptools.scripts.compile [OPTIONS] [SRC_FILES]...

  Compiles requirements.txt from requirements.in, pyproject.toml, setup.cfg,
  or setup.py specs.

Options:
  --version                       Show the version and exit.
...

Contributor checklist

• [ ] Included tests for the changes.
• [x] PR title is short, clear, and ready to be included in the user-facing changelog.

Maintainer checklist

• [x] Verified one of these labels is present: backwards incompatible, feature, enhancement, deprecation, bug, dependency, docs or skip-changelog as they determine changelog listing.
• [ ] Assign the PR to an existing or new milestone for the target version (following Semantic Versioning).

[chrysle]

Thanks! Could you add a functional test, please?

[jamesbraza]

@chrysle trying to do something like this, I am getting defeated by all the relative imports in compile.py. So I opened https://github.com/jazzband/pip-tools/pull/2024, then I can come back to this the test of __main__ behaviors

[webknjaz]

Is that instead of python -m piptools compile? Why?

[jamesbraza]

Oh yeah python -m piptools compile can work too actually, didn't know about that. I am not attached to this PR if there's an alternate path to the same solution. Feel free to close this out

[webknjaz]

Oh yeah python -m piptools compile can work too actually, didn't know about that. I am not attached to this PR if there's an alternate path to the same solution. Feel free to close this out

Yep. I think I discovered it by reading the code. It should probably be documented better.

[webknjaz]

Oh, it's actually mentioned here https://pip-tools.rtfd.io/en/latest/#example-usage-for-pip-compile.