Document `EXTRA_FUNCTIONALITY` and `decimal.IEEEContext`

[picnixz]

In #122081, the NEWS entry would be better if we had those documented features (as an RST entry, decimal.IEEEContext is already documented at the function level). I can work a PR now (@skirpichev, do you want to do it since you're more familiar with those features? (though I don't mind doing it if you don't have time))

[skirpichev]

I'm not sure if we should do this right now. There is a pr, that exposes this functional as public: #122003; it adds also docs.

There is a need to decide fate of this stuff in the decimal module. This is not tested with regular CI tests or with build bots, now we also have crash report #122081.

[picnixz]

Mmh. Now that I think about, how about this order:

• Fix crash first. No docs yet.
• Document the functionality (+ amend the news entry).
• Consider whether to expose it unconditionally or not.

[skirpichev]

Is there another similar case in stdlib?

[picnixz]

I'm not aware of it. I just think we shouldn't actually document something that crashes. So it's better to first fix the crash, document a feature that exists and is provided to the user via EXTRA_FUNCTIONALITY and decide whether this should be kept behind that flag or not.

Actually, what I find weird is that we do not document EXTRA_FUNCTIONALITY at all but still add documentation to IEEEContext as if they could be public (which I think it should be considered as such if we use EXTRA_FUNCTIONALITY). But I can't find any mention of EXTRA_FUNCTIONALITY in the docs (or even in the configure help).

[skirpichev]

I just think we shouldn't actually document something that crashes.

My doubts mostly about order of later points.

I find weird is that we do not document EXTRA_FUNCTIONALITY at all but still add documentation to IEEEContext

I would guess one was undocumented intentionally. But if you wish to document this option - it has a lot of stuff beyond just IEEEContext support. And all that (?) is missing in _pydecimal.

I think we should document something from that camp only if that will became enabled per default and ported to python's module.

[picnixz]

But if you wish to document this option - it has a lot of stuff beyond just IEEEContext support

AH! Ok, it makes sense now. I'll close the issue for now.