Refactor stash_utils submodule

[truth-quark]

The Stash class in stash_utils.py adds another object layer for accessing the ATM_STASHLIST lookup. This has a few problems:

• It introduces another layer of indirection
• New Stash instances are created every time a code is looked up.

Ideally, Stash should be refactored to a dict for simplification & provide a common Pythonic interface. Each code lookup should return an existing ATM_STASHLIST entry, negating the need to create a new Stash record object.

Tasks:

• Refactor amami/stash_utils/__init__.py to amami/stash.py (package to simple module) (see #20)
• Refactor Stash class:
  • Modify Stash class to inherit from UserDict
  • Implement custom __getitem__, __setitem__ to convert str, stash codes etc to int keys
  • Remove unused methods
  • Change ATM_STASHLIST to instance of the new Stash dict type
  • Refactor calling code to directly reference the lookup
  • Idea: use dicts or named tuples for the values?

More ideas (see #33):

• Move Stash lookup into um_utils module as it's part of unified model code
• Delete the stash_utils module

[atteggiani]

Refactor Stash class & ATM_STASHLIST to dict lookup (avoid Stash obj creation to convert/look up codes)

ATM_STASHLIST is already a dictionary. How do you want to refactor it? I haven't well understood the picture of the new structure you have in mind.

• Implement custom __getitem__, __setitem__ to work with str, stash codes etc

In the point below you mentioned removing the Stash class. Where do you want to implement the custom __getitem__ and __setitem__ methods?

• Remove existing Stash class, use dict interface for standard python interoperability

Not sure why you want to remove the Stash class. I believe having a STASH object is useful in many different subcommands (future ones as well).

• Move lookup to um_utils module as it's part of unified model code

We could move the Stash class to the um_utils module.

But I still haven't really understood the structure of such 'lookup' you refer to.

• Delete the stash_utils module

This can be done If we move the Stash class to the um_utils module.

[truth-quark]

Refactor Stash class & ATM_STASHLIST to dict lookup (avoid Stash obj creation to convert/look up codes)

ATM_STASHLIST is already a dictionary. How do you want to refactor it? I haven't well understood the picture of the new structure you have in mind.

• Implement custom __getitem__, __setitem__ to work with str, stash codes etc

In the point below you mentioned removing the Stash class. Where do you want to implement the custom __getitem__ and __setitem__ methods?

Ooops, I mucked up the original ticket text. This should be fixed, explaining refactoring the Stash class into a customised dict for the ATM list.

I'm currently working on an example of the above work in another branch...

[atteggiani]

Captured refactoring of stash_utils in #20

[truth-quark]

I'll reopen as it covers refactoring the custom Stashclass (which needs some tweaks to bring in line with Python conventions).

[atteggiani]

@truth-quark Please edit the body of this issue:

• to cover only the refactoring of the Stash class (without including the package to simple module refactor already mentioned in #20)
• to list specific modifications that you think need to be implemented for the Stash class

[truth-quark]

I've updated the issue/crossed out the structural changes from #33.

The class modifications need more thought, so I'll update that after another code experiment.