Make config template input-type independent.

[cwwalter]

This PR removes specifics of instance catalogs from the imsim-config.yaml. It is now input method independent.

It creates two new config files that use imsim-config.yaml as a template: imsim-instcat.yaml and insim-skycat.yaml. Eventually, with a new version of GalSim these will themselves become templates. But, nested templates are not yet implemented. So, for now, they serve as a template file for copying. The user copies them to a working area and adds the information they want to override at the bottom of the file below the template information. As we create new input methods we can add new files.

The files in config are not meant to be run. They are only config templates. The "examples" directory now contains imsim-user-instcat.yaml and imsim-user-skycat.yaml. These files reproduce the original functionality of the runnable config files.

Since I pulled out the (e.g)

gal:
    type: InstCatObj

stamp.world_pos:
    type: InstCatWorldPos

from the imsim-config file, this willl break things that don't set them as in the config templates for each input type. Will need to see what if anything breaks in the CI when I submit this.

Thoughts welcome.

[cwwalter]

@rmjarvis Folllowing @jchiang87 's suggestion. For now I am just manually copying all of the original template information into the top of (e.g.) imsim-config-instcat.yaml. When the new version of GalSim is being used generally, we will replace that with a template call. So the template file looks like this:

[content of imsim-config.yaml]

################################################################
#  Above is template material.
#
#  Make changes specific to this input method below.
#  When GalSim allows nested templates we will replace this with a
#  template call
################################################################

input.instance_catalog:
    # This should be overridden below or on the command line.
    file_name: default_catalog_file.txt
    sed_dir: $os.environ.get('SIMS_SED_LIBRARY_DIR')

... more overrides...

But when I try to use this in example/imsim-user-instcat.yaml. with

# Get most of the configuration from the imSim config-template
# for instance catalogs.
template: imsim-config-instcat

input.instance_catalog.file_name:  SOME_FILENAME
...

It doesn't work. I just get

galsim.errors.GalSimConfigError: Unable to parse extended key input.instance_catalog.file_name.  Field instance_catalog is invalid.

It is ignoring my override at the end of the template file. Is this a YAML issue of some sort? Should this work?

[cwwalter]

For now to get something to work I am manually inserting the yaml elements into a copy of the config section in each config file. This is dangerous... Hopefully this will be replaced by a nested template soon.

We have to be careful to not let config files get out of sync. Now nothing should be using the core imsim-config.yaml file. Everything (that uses a file input) should use a specific input type template.

[cwwalter]

OK this now passes all tests and should be exactly equivalent to before in usage.

When the nested templates work in GalSim, we will replace the pasted common yaml int he config files with a imsim-config template call and override what is needed in the specific input config. This will be invisible to users, a completely internal change.

[cwwalter]

I think Mike is on vacation this week. Could you review Jim?

[jchiang87]

Most of my change requests are stylistic, so not totally essential, but I think would clarify things for new users. One important change, however: If the yaml files in the config folder are supposed to be templates and not run directly, I'd suggest moving the flat*yaml files to the examples folder (and update the CI yaml).

[cwwalter]

Thanks Jim. I also moved the flat files to examples as you suggested.

[jchiang87]

Thanks, Chris. LGTM.

[cwwalter]

I think this is ready to merge. @rmjarvis when you get a chance could you either add anything new or clear your request for a change (now discussed in #397?).