issue_comments

thanks for the PR, @marscher, and especially for being patient with us/me.

if the CI still passes without the explicit mention of setuptools in the CI environments this should be ready for merging. It would probably be good to review the change to the dependency policy, though (do we need to list setuptools even if we only depend on it at build time?)

the CI passes, too. Now we just need an entry in whats-new.rst saying that the runtime dependency on setuptools was dropped, and we might also want to remove the explicit mention of setuptools in the CI files

thanks, @dopplershift. We agreed on doing that in the last meeting, and to then drop the new dependency together with python=3.7 in December. That means that if we can figure out the remaining issues we can include this in the next release (which will be very soon!)

I might be confusing something, but I thought preprocessing selectors were executed at build time? So if you build the noarch: python package in an environment that has python=3.7 you will keep the importlib_metadata while in a different one with python=3.8 it will be removed?

The easiest way to figure this out would be to build in a py38 environment, install in a py37 environment and then try to import it (i.e. trigger the code path that uses importlib.metadata). If that works, then it would be fine to merge now.

is there any reason not to merge this?

the issue is that with conda we can either always install importlib_metadata or not at all: conda doesn't support noarch_python packages with preprocessing selectors (see the comments around https://github.com/pydata/xarray/issues/4295#issuecomment-667657310 for more discussion).

importlib.metadata is included in python>=3.8, which we can officially require from end of December this year.

All of this means that if we want to merge this now we have to decide between not releasing until we can drop python=3.7 or always installing importlib_metadata (which is what the pint feedstock does). However, I guess the cleanest way would be to wait until we can require python>=3.8.