Why I would default to choosing sequence over list when adding types to a function

A blog post on choosing more specific types rather than general ones like list and dict.

  • qwertyasdef@programming.dev
    1·
    2 years ago

    If you don’t need to reuse the collection or access its items out of order, you can also use Iterable which accepts even more inputs like generators.

  • jadelord@discuss.tchncs.de
    1·
    2 years ago

    Good point, and Łukasz Langa mentioned this in his talk (check it out). He names it the robustness principle, in his words (around 22:20 mark:

    “Vague in what you accept, concrete in what you return”

    But he also mentions some gotchas like how Iterable[str] can backfire, because str is also an Iterable[str] and it might be better to use list[str].

  • chemacortes@programming.devEnglish
    1·
    2 years ago

    Sequence now lives at collections.abc. BTW, float is not a supertype of int (issubclass(int, float) == False). Normaly, It is acceptable to use int instead of float, but speaking of variance, it is more precise to use numbers.Real:

    issubclass(Integral, Real) == True
issubclass(int, Real) == True
issubclass(float, Real) == True
issubclass(complex, Real) == False