gh-133143: Make information about the interpreter ABI more accessible

[zklaus]

This adds a new sys.abi_info object to make basic abi information more readily accessible.

The basic idea is to have not just flags as originally envisioned in #133143, but rather a more pythonic object with the required information, following the model of the sys.thread_info and sys.int_info object as suggested in the discussion by @encukou.

gh-133143

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[encukou]

This is a big PR!
I'll ask you to simplify (and, alas, throw a lot of the scaffolding work away...)

[zklaus]

Thanks for your review, @encukou! I think I have addressed all of your comments and, as you anticipated, it simplifies things a great deal.

Would you mind taking another look?

[encukou]

Looks good now, thanks!
It does need a test. (Ideally comparing things to sys.maxsize and sysconfig.get_config_var, which should also serve as guide/validation for what the packaging tools will need to do for earlier Python versions.)

And, of course, it needs deciding on what should go here; but that's for the discussion thread.

[zklaus]

Agreed about the tests and further discussion. I just wanted to stabilize the implementation sufficiently to be sure to write meaningful tests. Thanks again!

[zklaus]

Tests are in place and easily extendable. Let's focus on the discussion and get this in 💪.

[vstinner]

Can you also mention the new sys.abi_info in Doc/whatsnew/3.15.rst document? You should add a new "sys" section in https://docs.python.org/dev/whatsnew/3.15.html#improved-modules

[vstinner]

LGTM

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[zklaus]

@encukou, I think the two test failures are unrelated to this PR (both from tarfile, fixed in #138626).

Is there anything left that I should do?

[encukou]

Could you add semantic Sphinx syntax for .. attribute::, from zklaus#3 ? Sorry I didn't link to it on Friday.

With that, I consider this good to merge :)

[zklaus]

Done, thanks!

[AA-Turner]

oops, I meant to push to my own branch to propose a PR to @zklaus's repo, sorry. Given Petr has enabled auto-merge already I'll propose my changes in a follow-up.

Separately, should we use a named type for abi_info? Currently the repr shows namespace, which could be surprising for users:

❯ .\python.bat
>>> import sys
>>> sys.abi_info
namespace(pointer_bits=64, free_threaded=False, debug=True, byteorder='little')

A

[vstinner]

Separately, should we use a named type for abi_info?

I don't think that using namespace is a big deal here.

[vstinner]

Congrats @zklaus, your PR was merged :-)

[encukou]

should we use a named type for abi_info?

sys.implementation is a namespace too, and I haven't seen any complaints.
(float_info and such are separate types with iter & getitem for compatibility with long-gone Pythons where these were tuples. The names are nice, but not worth the complexity for new stuff.)

[AA-Turner]

I realised that one drawback of using SimpleNamespace is that the namespace is not immutable, unlike e.g. sys.version_info, sys.int_info, etc. I'm happy to continue using it given @vstinner & @encukou's comments, but perhaps we should override __setattr__? All the other _info namespaces in sys are immutable, sys.implementation seems to be the exception as far as I can tell.

A

[encukou]

No need. This is Python; consenting adults; you break it you get to keep the pieces; etc.

You can already set sys.int_info = type(sys.int_info)([5, 8, 23, 864]) for example.

[merwok]

e.g. would have been better spelled out as for example