Clean Functions
F1: Too Many Arguments (Maximum 3)
python# Bad - too many parameters def create_user(name, email, age, country, timezone, language, newsletter): ... # Good - use a dataclass or dict @dataclass class UserData: name: str email: str age: int country: str timezone: str language: str newsletter: bool def create_user(data: UserData): ...
More than 3 arguments means your function is doing too much or needs a data structure.
F2: No Output Arguments
Don't modify arguments as side effects. Return values instead.
python# Bad - modifies argument def append_footer(report: Report) -> None: report.append("\n---\nGenerated by System") # Good - returns new value def with_footer(report: Report) -> Report: return report + "\n---\nGenerated by System"
F3: No Flag Arguments
Boolean flags mean your function does at least two things.
python# Bad - function does two different things def render(is_test: bool): if is_test: render_test_page() else: render_production_page() # Good - split into two functions def render_test_page(): ... def render_production_page(): ...
F4: Delete Dead Functions
If it's not called, delete it. No "just in case" code. Git preserves history.
