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pythonfunctionvarpython-typing

Type Hinting List of Strings

In python, if I am writing a function, is this the best way to type hint a list of strings:

def sample_def(var:list[str]):

Solution

  • I would use the typing module

    from typing import List

def foo(bar: List[str]):
    pass

    The reason is typing contains so many type hints and the ability to create your own, specify callables, etc. Definitely check it out.

    Edit:
    I guess as of Python 3.9 typing is deprecated (RIP). Instead it looks like you can use collections.abc.*. So you can do this if you're on Python 3.9+:

    from collections.abc import Iterable

def foo(bar: Iterable[str]):
    pass

    You can take a look at https://docs.python.org/3/library/collections.abc.html for a list of ABCs that might fit your need. For instance, it might make more sense to specify Sequence[str] depending on your needs of that function.