Replace pep425tags w/ packaging.tags

[brettcannon]

It's the entire reason packaging.tags was written to support Python 2.7. 😄 Plus packaging.tags has a much more thorough list of potential tags than pep425tags has, so it should lead to more wheels being flagged as supported (especially for PyPy and other alternative VMs).

Link to packaging.tags: https://github.com/pypa/packaging/blob/master/packaging/tags.py

[cjerdonek]

Are there any plans to add type annotations to packaging.tags? pep425tags is one of the modules in pip that is fully annotated, so it’d be nice to at least stay the same on that front..

[cjerdonek]

Also, do you recall the date / commit hash when packaging.tags was forked from pep425tags? That would let people review the changes to pep425tags since then to make it easier to see that feature parity is being preserved.

[pradyunsg]

Another thing that's needed is being able to generate tags for a different platform/version/implementation/abi, IIUC.

    :param versions: a list of string versions, of the form ["33", "32"],
        or None. The first version will be assumed to support our ABI.
    :param platform: specify the exact platform you want valid
        tags for, or None. If None, use the local system platform.
    :param impl: specify the exact implementation you want valid
        tags for, or None. If None, use the local interpreter impl.
    :param abi: specify the exact abi you want valid
        tags for, or None. If None, use the local interpreter abi.

And noarch, for only generating "none" tags.

[di]

We also probably want a new release of packaging before we can do this (to avoid vendoring attrs in).

[brettcannon]

@cjerdonek no specific plans for type annotations, but I personally have no issue adding them. Probably a broader question of whether 'packaging' itself wants to go down the route of adding type annotations.

As for when it was forked, it was never actually forked. 😄 I wrote packaging.tags from scratch and tried to match the semantics of pep425tags as reasonable but also expand them where I thought it was falling short. But if you want a rough date, probably Dec 14, 2018 when I created the PR. But I did check earlier this week whether there were tag differences at least on Windows and I fixed the one critical case.

@pradyunsg expanding the API to allow for that wouldn't be hard. First pass on the module specifically kept the API small. If you want me to start thinking about how to let sys_tags() or some new function take specific details then I can. Just open an issue on 'packaging' and assign it to me with the exact details of what you need to allow for specifying (e.g. do you explicitly need separate versions or separate interpreter versions, IOW do you want to specify by wheel tag or lower-level breakdown?).

@di I assumed a release would be made when pip was ready to roll up everything that has gone in at this point. For me the key point of doing this issue was to make sure folks like @cjerdonek were aware that packaging.tags existed so if something happened to pep425tags it could also get flagged down to packaging.tags.

[cjerdonek]

Probably a broader question of whether 'packaging' itself wants to go down the route of adding type annotations.

@brettcannon I think that would be a good idea. I don't think all of packaging would need to be annotated before incorporating packaging.tags, but I think at least annotating tags before then would be good.

Also, in terms of behavior and features, are there any differences with pep425tags that you're aware of (aside from pep425tags being incomplete)? Have you checked? I know, for example, that there's a case where pep425tags will log debug messages:

pip/src/pip/_internal/pep425tags.py

Lines 93 to 98 in 2985efe

	val = get_config_var(var)
	if val is None:
	if warn:
	logger.debug("Config variable '%s' is unset, Python ABI tag may "
	"be incorrect", var)
	return fallback()

but packaging.tags doesn't seem to do any logging.

PS - I added a link to packaging.tag's source file in your original comment.

[pradyunsg]

open an issue on 'packaging' and assign it to me with the exact details of what you need to allow for specifying

Done! Here it is: pypa/packaging#187

[pradyunsg]

We also probably want a new release of packaging before we can do this (to avoid vendoring attrs in).

I don't think this'd be finished before the next release cycle of pip TBH. So, the lack of a packaging release isn't a major concern to me. I'm pretty sure we'll get to it before this. ^>^