Various ruff fixes

[cclauss]

Describe your change:

Make changes required to pass current ruff tests.

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Add or change doctests? -- Note: Please avoid changing both code and tests in a single pull request.
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms include at least one URL that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues then the description above includes the issue number(s) with a closing keyword: "Fixes #ISSUE-NUMBER".

[cclauss]

@dhruvmanila I do not understand this change requested by ruff. Type hints are suggestions, not mandatory in Python. Just because the type hint says num: int, that does not guarantee that the caller will not pass in 17.23. This call to round() prevents breakage.

[dhruvmanila]

I think this is correct and is https://docs.astral.sh/ruff/rules/unnecessary-round/. The num is an int so it doesn't require a round call. If you expect num to be a float as well then the type hint should be updated to int | float which is basically float.

[cclauss]

This misses the point. The type hint is a suggestion in Python, not an obligation. The caller may choose to send a float even though I have suggested they send an int. Without the round() call, the function will crash. With the round() call, the function will succeed. This rule is asking me not to drive defensively.

The workaround for ruff rule RUF057 is to use int(num) instead of round(num):

• hill_cipher.py: Use int() to gracefully deal with float input #12833

[dhruvmanila]

I don't think that's correct. From a static analysis perspective, type hints are part of the function contract that says that the num parameter here should be an int and if the caller passes a float then that's an error. So, if the function is expecting to receive a float or an int, then the contract should be updated instead.

[cclauss]

The num parameter here should be an int. Python will not prevent the caller from breaking that rule.

Using int(num) instead of round(num) ensures the function remains well-behaved in the face of garbage input.

[dhruvmanila]

I see. I think that depends on whether this specific function is part of the public API for this module or not. If it is, then one way to perform error handling would be to use something like:

if not isinstance(num, int):
    raise TypeError("expected an integer, but got ...")

And, if it's not part of the public API, then we shouldn't do this and instead use a type checker.