Hi, following up http://mail.python.org/pipermail/docs/2011-February/003083.html we have a chat on #python-dev on the topic, the situation is

- all started with os.lchmod() and as.lchflags() methods not available on a Debian system
- that's because POSIX does not require those functions and then Linux systems don't provide them 
- so we then thought about clarifying, only for those 2 methods, that they might not be available with a format like "availability: some unix systems"
- then we noticed that on top of os doc there's a notice "An “Availability: Unix” note means that this function is commonly found on Unix systems. It does not make any claims about its existence on a specific operating system." and so we thought about linking every 'Availability: Unix' to that note
- or transform that not in a footnote and link every 'Availability: Unix' for functions that might not be present to that footnote.

It's enough for the conversation dump: ideas/suggestions? :)

I like the footnote idea.

I wonder if it would also be worth marking which functions are Posix (Availability: posix) and therefore likely to be available on all unix systems.

> I like the footnote idea.

Me too.

> I wonder if it would also be worth marking which functions are Posix
> (Availability: posix) and therefore likely to be available on all unix 
> systems.

POSIX has optional APIs, hasn't it?

Good point :(

The "Notes on availability" bullet list at the top of docs.python.org/library/os should already say everything that there is to say here...

Yes, but when you jump directly to one of the functions, you don't see that bullet list.  Whereas if it were a footnote on the 'avaiability: unix" statement, the natural thing would be to follow the footnote and thus learn the limitations on that statement.  Thus I think the footnote would be better than the bullet list at the top.

That's a good point, indeed.

In another issue Georg came up with the idea of creating an availability directive that would auto link to the appropriate text.  This would then apply to all our different availability types.

If no-one else has started on this, I’m interested in making a patch to introduce an availability directive.

A draft is attached.  The directive currently just always links to the "availability" notes, which I have moved to the main "Operating system services" document.  Please review!

I can't comment on the Sphinx extension code but this is a good idea.

I like the idea of a single place where the Availability is described, and adding a link to this place.  availability-directive.patch LGTM.

Hello,

It doesn't appear that this patch was ever merged.  If there's still interest, would it be OK for me to convert it to a PR?

Thanks!

A PR for this would be good, and would certainly accelerate getting this accomplished.  Thanks, Cheryl!

Thanks, Fred.  I've submitted the PR.

New changeset 2d6097d027e0dd3debbabc702aa9c98d94ba32a3 by Victor Stinner (Cheryl Sabella) in branch 'master':
bpo-11233: Create availability directive for documentation (GH-9692)
https://github.com/python/cpython/commit/2d6097d027e0dd3debbabc702aa9c98d94ba32a3

New changeset b248a8c9a5e7cf6b8e84a3efda493fccfc511316 by Victor Stinner (Cheryl Sabella) in branch '3.7':
[3.7] bpo-11233: Create availability directive for documentation (GH-9692) (GH-9830)
https://github.com/python/cpython/commit/b248a8c9a5e7cf6b8e84a3efda493fccfc511316

Thank you Sandro Tosi for the bug report, thanks Georg Brandl for initial patch, and thanks Cheryl Sabella for the final changes in 3.7 and master!

According to Yury Selivanov, it's not need to backport this change to 2.7 and 3.6, so I close the issue.
https://github.com/python/cpython/pull/9692#issuecomment-429364037

And thank you, Victor, for reviewing and merging!  :-)