Add type hints for generators and accessors

[maxrjones]

Description of proposed changes

Making it easier to catch errors, for example for dataset/dataarray differences.

Fixes #

[codecov-commenter]

Codecov Report

Merging #128 (022ebf7) into main (e976d76) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #128      +/-   ##
==========================================
+ Coverage   97.97%   97.98%   +0.01%     
==========================================
  Files           5        5              
  Lines         198      199       +1     
  Branches       35       34       -1     
==========================================
+ Hits          194      195       +1     
  Misses          4        4              

Impacted Files	Coverage Δ
xbatcher/accessors.py	100.00% <100.00%> (ø)
xbatcher/generators.py	100.00% <100.00%> (ø)

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[jhamman]

Suggested change

	def _iterate_batch_dims(self) -> Any:
	def _iterate_batch_dims(self) -> Generator[Dict[str, int], None, None]:

I didn't test this but I think it is basically right. If it works, you can propagate this to the _iterate_through_dataset function as well.

[jhamman]

Alternatively, you can use the Iterator type.

[maxrjones]

Lots of errors using def _iterate_batch_dims(self) -> Iterator[Dict[Hashable, slice]]:.

xbatcher/generators.py:182: error: Keywords must be strings
xbatcher/generators.py:182: error: Argument 1 to "isel" of "Dataset" has incompatible type "**Dict[Hashable, slice]"; expected "Optional[Mapping[Any, Any]]"
xbatcher/generators.py:182: error: Argument 1 to "isel" of "Dataset" has incompatible type "**Dict[Hashable, slice]"; expected "bool"
xbatcher/generators.py:182: error: Argument 1 to "isel" of "Dataset" has incompatible type "**Dict[Hashable, slice]"; expected "Literal['raise', 'warn', 'ignore']"
xbatcher/generators.py:182: error: Argument 1 to "isel" of "DataArray" has incompatible type "**Dict[Hashable, slice]"; expected "Optional[Mapping[Any, Any]]"
xbatcher/generators.py:182: error: Argument 1 to "isel" of "DataArray" has incompatible type "**Dict[Hashable, slice]"; expected "bool"
xbatcher/generators.py:182: error: Argument 1 to "isel" of "DataArray" has incompatible type "**Dict[Hashable, slice]"; expected "Literal['raise', 'warn', 'ignore']"
xbatcher/generators.py:189: error: Argument 1 to "list" has incompatible type "Iterator[Dict[Hashable, slice]]"; expected "Iterable[List[Dict[Hashable, slice]]]"
Found 8 errors in 1 file (checked 20 source files)

I have a separate refactor almost finished that would fix #131 and make this function obsolete. Do view it as necessary to type all functions before merging in the existing type hints? My preference would be to not spend more time on this.

[jhamman]

@maxrjones - this is great. Is mypy active in one of the CI environments? I didn't see it but I could have missed it.

[maxrjones]

@maxrjones - this is great. Is mypy active in one of the CI environments? I didn't see it but I could have missed it.

Thanks for the reviews @jhamman! Mypy is activate via the pre-commit CI (e.g., https://results.pre-commit.ci/run/github/155272397/1668812992.ah7CK-WJSvCUCBL9ANdLhA).