[python] Add type hints to helpers/parameter_generator.py

[sagnik1511]

contributes to #3756

Added type hints on helpers/parameter_generator.py

[ghost]

All CLA requirements met.

[jameslamb]

Thanks for your help! Please see the suggestions from my first review. You can accept them directly in the browser by clicking "add to batch" here on GitHub, then "commit suggestions".

These suggestions could be summarized by these three practices:

• when using types which can contain instances of other types, add type hints for those contents. For example, a list of tuples of 3 integers should be List[Tuple[int, int, int]], not List
• only use Optional for something which can be None
• give functions which explicitly return None or implicitly return it by not having any return statements the return hint -> None

[sagnik1511]

Thanks, @jameslamb for reviewing, I understood that the codes should be more specific and less coded. Thank You, sir.

[jameslamb]

Thanks very much!

I found some additional issues by running mypy helpers/parameter_generator.py.

helpers/parameter_generator.py:31: error: Need type annotation for 'cur_info' (hint: "cur_info: Dict[<type>, <type>] = ...")
helpers/parameter_generator.py:33: error: Need type annotation for 'member_infos' (hint: "member_infos: List[<type>] = ...")
helpers/parameter_generator.py:126: error: Invalid tuple index type (actual type "str", expected type "Union[int, slice]")
helpers/parameter_generator.py:127: error: Invalid tuple index type (actual type "str", expected type "Union[int, slice]")
helpers/parameter_generator.py:291: error: Argument 1 to "get_names" has incompatible type "List[Dict[str, Any]]"; expected "List[List[Dict[str, Any]]]"
helpers/parameter_generator.py:292: error: Argument 1 to "get_alias" has incompatible type "List[Dict[str, Any]]"; expected "List[List[Tuple[Dict[str, Any]]]]"
helpers/parameter_generator.py:328: error: Invalid index type "str" for "str"; expected type "Union[int, slice]"
helpers/parameter_generator.py:329: error: Invalid index type "str" for "str"; expected type "Union[int, slice]"
helpers/parameter_generator.py:330: error: Need type annotation for 'checks' (hint: "checks: List[<type>] = ...")
helpers/parameter_generator.py:332: error: Incompatible types in assignment (expression has type "str", variable has type "List[Any]")
helpers/parameter_generator.py:332: error: Invalid index type "str" for "str"; expected type "Union[int, slice]"
helpers/parameter_generator.py:343: error: Invalid index type "str" for "str"; expected type "Union[int, slice]"
helpers/parameter_generator.py:344: error: Invalid index type "str" for "str"; expected type "Union[int, slice]"
helpers/parameter_generator.py:359: error: Incompatible return value type (got "Tuple[List[Tuple[str, int]], List[Dict[str, Any]]]", expected "Tuple[List[Tuple[str, int]], List[List[Dict[str, Any]]]]")
Found 14 errors in 1 file (checked 1 source file)

I pushed sagnik1511@11ed4b3 to this branch to fix them.

[sagnik1511]

Thank You @jameslamb, for that.
Can I try to update other files?

[jameslamb]

Can I try to update other files?

Sure, please open a new pull request if you'd like to update a new file. Please consider the suggestion in #4474 (review) when you do that.

[StrikerRUS]

I think we can be even more precise and use List instead of Any:

[StrikerRUS]

LGTM, thank you!

[sagnik1511]

@StrikerRUS, @jameslamb, thank you for letting me collaborate. Please, do merge this PR :)

[jameslamb]

Sorry for the delay in merging, thanks again for the help!

[github-actions]

This pull request has been automatically locked since there has not been any recent activity since it was closed. To start a new related discussion, open a new issue at https://github.com/microsoft/LightGBM/issues including a reference to this.