specsim desimodel dependency

[weaverba137]

I'm not sure where this was introduced, but a dependency on desimodel has been introduced into specsim, which means that specsim is no longer independent of the DESI software stack. Furthermore, desimodel required desiutil, so that's two DESI packages.

In contrast, speclite is still independent of the DESI software stack.

What is the long-term intention for specsim maintenance in this regard?

[dkirkby]

My intent is that there are no python import dependencies on any DESI packages.

The only (soft) dependency should be that the desi.yaml file refers to paths within $DESIMODEL.

[weaverba137]

OK, but that's not what I see in the code. Both specsim.instrument and specsim.fastfiberacceptance import desimodel.fastfiberacceptance. I do see other references to $DESIMODEL which is probably OK, but those import statements definitely create a dependency.

[dkirkby]

That came from #114 from @julienguy but I don't remember why this was needed. Hopefully he can comment here.