mypy warnings

This page explains some mypy warnings in the code that can be ignored.

Last updated: 2023-01-23, v0.2.0.

• arg-type errors in:

  • src/codepost_powertools/_utils/file_io.py

  • src/codepost_powertools/rubric/rubric_to_sheet.py

  • src/codepost_powertools/grading/ids.py

  [file_io.py:137] Argument 3 to "handle_error" has incompatible type "Optional[str]"; expected "str"
  [rubric_to_sheet.py:766] Argument 1 to "_get_worksheets" has incompatible type "Optional[Spreadsheet]"; expected "Spreadsheet"
  [ids.py:151] Argument 2 to "save_csv" has incompatible type "Optional[Path]"; expected "Union[PathLike[Any], str]"
  

  These errors involve the SuccessOrNone[T] and SuccessOrErrorMsg types. They are defined as a tuple with a “success” flag and something else, with the types when success = True and when success = False different but still exactly defined. Thus, if there is an if statement checking the value of success, the other value’s type is definitely known within the body. However, mypy does not recognize this, and gives errors.

  Additional conditionals can be put into the if statements to also check if the other value is None, but that would be redundant and only for the purpose of satisfying the type-checker. We have decided that that is not a good enough reason to change the code, and instead this error will remain. However, this means that more instances of this error will likely come up as more code is written.