Edge cases for enums in InputSpec

[rjoussen]

TODOs

• Fix broken assignment: e.g. may not assign Validator<int> to Validator<optional<int>> (Disallow non-optional to optional Validator assignment #1719)
• Fix enum choices and descriptions not being fully compatible
• Fix enum inside vector (write out choices to metadata in this case)
• Fix optional enum metadata emit (Emit optional enum choices to metadata #1720)

Interested Parties

[sebproell]

With #1720, I was able to make ENTITY_TYPE optional by modifying this:

4C/utilities/four_c_python/src/four_c_metadata/metadata.py

Lines 409 to 416 in 78d81cf

	super().__init__("enum", name, description, required, noneable, validator)
	if check_if_set(default):
	if default not in choices:
	raise ValueError(
	f"Default choice {default} is not in the valid enum choices {choices} of {name}"
	)
	self.choices = choices
	self.default = default

with an additional

        if noneable:
            choices = list(choices) + [None] 

before line 410.

@rjoussen @gilrrei I leave it to you whether this is the correct fix on the Python side, or if you want to handle it differently.

[rjoussen]

    if noneable:
        choices = list(choices) + [None] 

Looks good to me, but shouldn't that be part of #1720 maybe? Otherwise optional enums as introduced by #1720 can only be used if the default value is not null_opt/None.

[gilrrei]

@sebproell @rjoussen sounds good :) Just as a reminder, we should also change the typehinting

4C/utilities/four_c_python/src/four_c_metadata/metadata.py

Line 389 in 78d81cf

choices: Sequence[str],

to

        choices: Sequence[str | None],