Consider python specific options via --pip-args

[atugushev]

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[atugushev]

This allows targeting specific Python versions:

$ echo click | pip-compile - -qo- --no-header --no-annotate
click==8.1.3

$ echo click | pip-compile - -qo- --no-header --no-annotate --pip-args='--python-version=3.0.0'
click==6.7

cc: @mitsuhiko

[chrysle]

Looks good, but this will need a test.

[chrysle]

@atugushev This would need merging for the feature worked on in #1998. Could you add a test?

[atugushev]

@chrysle I'm inclined to close this, as is may not work as expected.

[chrysle]

@atugushev Could you elaborate on that?

[georgek]

@atugushev would love to know more about what you don't think would work as expected. I was looking to build upon this to enable the correct default behaviour of pip-tools when installed by pipx or as a system package etc.

[chrysle]

@atugushev Gentle ping.

[atugushev]

My initial intent was to target a specific Python interpreter. I thought --python-version was the solution. However, it is only used for wheel and "Requires-Python" compatibility checks, as stated in the documentation:

$ pip install --help
...
  --python-version <python_version>
                              The Python interpreter version to use for wheel and "Requires-Python"
                              compatibility checks. Defaults to a version derived from the running
                              interpreter. The version can be specified using up to three dot-
                              separated integers (e.g. "3" for 3.0.0, "3.7" for 3.7.0, or "3.7.3").
                              A major-minor version can also be given as a string without dots (e.g.
                              "37" for 3.7.0).

I know there is a --python <python> option, however it runs pip in a subprocess which doesn't work well with the pip-tools resolver.

[georgek]

It sounds like this approach might be ruled out for the purposes of #1998 then. But just for my own curiosity and perhaps to help others look for this:

What difference is there in practice between targeting a specific interpreter vs specifying --python-version?

What is the problem with pip-tools and --python? Could pip-tools be changed to work better with this option?