Constrain package 'feature' to certain python versions or platforms?

[amosaikman]

Is it possible to constrain a package 'features' using extras syntax to only be installable when using certain Python versions or platforms — and maybe other conditions? For example:

[project.optional-dependencies]
feature = [
  "pkg1; python_version ~=3.10",
  "pkg2",
]

Will install pkg1 on Python 3.10 only but will still install pkg2 on every other version. What I want is to make feature installable only on Python 3.10 (and/or some other condition) such that an error is raised if a user attempts to do pip install mypackage[feature] using some Python version other than 3.10 (or whatever the condition might be). Presumably this is possible, but I can't immediately see how to do it. Thanks!

[ofek]

It's not possible to make a user facing error like that actually. The best you can do is provide an error at runtime.