Marten van Kerkwijk

OK, let's merge! Thanks, @maxnoe -- also for another nice exchange where we ended up on a simple solution!

Looking at this again, I continue to wonder slightly about the approach. Partially it is that I remembered that we put in place another mechanism to deal with unrecognized units,...

Coming back to this I'm still not sold on this solution, though perhaps practicality beats purity. However, for sure this needs proper documentation! Even just documenting a hacky way where...

OK, will try to have look!

Moving this over from the issue and editing numbers... Now had a look: I think the machinery looks really good! I'm actually somewhat impressed with our system that it ended...

I'm confused about "FOV LON should increase with decreasing OTHER LON" since I think this is not true for the current `SkyOffsetFrame`...

What about `astropy/utils/codegen.py`? That seems fairly appropriate since we are creating new classes!

I think `abcs` is very non-descriptive - the implementation via an `ABC` is logical, but not required (after all, it wasn't done that way before...). I still like `codegen`, and...

On the next steps, no, I don't think we need a separate set of tests; we don't do those for `ShapedLikeNDArray` either. But unlike I did for `ShapedLikeNDArray`, it would...

In the first instance, it would make sense to keep the code in the same file, though definitely a new decorator is introduced here... And while I still feel `codegen`...