Exposecm

[marqh]

a simple rebase of
#1981

[DPeterK]

Note the fact that this is just a rebased version of #1981 means that it retains that PR's unanswered question relating to cf_var_name. Options:

• we merge this as it is, which has the advantage of being nice and quick but the disadvantage of potentially introducing lower-quality code into Iris. That said, apparently cell methods parsing has worked since it was introduced, so it can't be that bad...
• we wait for the extra effort to get to the bottom of the issue, decide whether it is an issue, make the relevant changes, test them, remove/edit other tests, and then try to get this merged. Oh, and we potentially need to wait for the xarray guys (see comment to this effect). Benefits... higher quality code; downsides... missing the 1.10 milestone.

Considering these, I'm in favour of the former - we can add missing stuff later. @pelson @bjlittle thoughts? You both have prior on these changes.

[DPeterK]

I guess this should also have a whatsnew entry.

[marqh]

I guess this should also have a whatsnew entry.

added

+1 for

merge this as it is

[DPeterK]

Good stuff @marqh, I'm merging. Follow-up work can be done as a follow-up once it's better understood what, if anything, needs to be done about cf_var_name.

[DPeterK]

Thanks to @rhattersley (for originally doing the work) and @marqh (for updating) 🎉

[pp-mo]

we merge this as it is,...
apparently cell methods parsing has worked since it was introduced, so it can't be that bad..
we wait ... decide whether it is an issue

Re-reading, I don't think there is any outstanding functional problem, and I wasn't proposing we should enhance the routine : I'd like it to be a bit clearer about what it can and can't handle, and cover that in the documentation.

I don't think the xarray related issue makes any difference at this point.

Ideally, we would remove the functionally superfluous 'cf_name' arg.
As a minimum, just enhance the documentation + move on.

you merged it ?!!

[DPeterK]

I'm in favour of the former - we can add missing stuff later

you merged it?!!

Yes. Feel free to add anything you feel is missing; I didn't feel anything was missing that was dramatic enough to add yet further drag to the 1.10 release .

[pp-mo]

Feel free to add anything you feel is missing

Fair enough !!
I was just preparing a suggested tweak. I may as well complete it, and will post separately..