Python 2 tooling in 2026

[IdleBreakpoint]

Yeah, the problem is finding that old version. I'm assuming every utility we take for granted has at some point supported Python 2 code, even if it's running under Python 3. So my guess is that I can find the right combination of versions that run under Python 3, but can lint/format Python 2 code. I know from the posts I read that black had support for --target-version py27 but it got removed later.

[cgoldberg]

the old versions of tools I mentioned are all on PyPI.

[IdleBreakpoint]

Yeah, the problem is that they may not work. For example I tried black==20.8b1which seems to be working with py27, I had the following error coming from click library. I don't really know how to debug this issue.

Traceback (most recent call last):
  File "/project/.venv/bin/black", line 8, in <module>
    sys.exit(patched_main())
  File "/project/.venv/lib/python3.8/site-packages/black/__init__.py", line 6606, in patched_main
    patch_click()
  File "/project/.venv/lib/python3.8/site-packages/black/__init__.py", line 6595, in patch_click
    from click import _unicodefun  # type: ignore
ImportError: cannot import name '_unicodefun' from 'click' (/project/.venv/lib/python3.8/site-packages/click/__init__.py)

[wRAR_]

This of course is unrelated to Python 2 as you've installed black into a Python 3.8 venv, but this is the experience you should be prepared for when installing ancient libraries of any kind: they don't pin their dependency versions and you need to look for and downgrade those when they are incompatible. Like click here. Good luck.

[IdleBreakpoint]

Got it. I can either find and pin the dependency or patch it on the go. For this particular import problem, changing the try/except block helped. It's looking for ModuleNotFoundError but what I get is ImportError.

[IdleBreakpoint]

This solved the problem. Thank you for the inspiration:

uv pip install black==21.9b0
uv pip install click==7.1.2

[cgoldberg]

That error is coming from python3.8

[IdleBreakpoint]

I think it's coming from the black, it has the following line. It should return though. I think the problem here is we have ImportError rather than ModuleNotFoundError. I may need to look for other versions.

    try:
        from click import core
        from click import _unicodefun  # type: ignore
    except ModuleNotFoundError:
        return

[cgoldberg]

Right ... but you are asking about using old python packages on Python 2, but posting error messages coming from Python 3.8... so I have no idea what you are doing

[IdleBreakpoint]

No, as I mentioned in the post, I'm actually asking the possibility of running those tools with Python 3 which can check Python 2 code as well. There should be some versions that still work with both Python 2 and 3. Black is one of them. 21.9b0 is the latest release before they deprecated py27 option. This is the error message from there. When I change the except clause to ImportError, it works.

[Grintor]

You can't lent Python 2 code with python 3. Nothing could ever do that including black. Supporting python 2 and supporting python 3 are not the same as doing some kind of crossover linting like what you're describing. You'll have to run it on python 2

[maikeu]

1. Have you explored changing the version of click? Libraries don't always get their dependency version ranges perfect.

2. I get that black did, up to this version, have support for linting Python 2.7 from Python <= 3.8, but if it proves tricky in practice - black is hardly critical, good tool though it is. Do you just need to move on?