Python Type Checking: Summary

Great info! Not sure if I missed this but hints would work for user defined types as well right?

Yes, type hints work great for user defined types as well.

I don’t think it’s covered in the videos, but you can find some information about using your own classes as types in the article the videos are based on (see the Supporting Material link under the video): realpython.com/python-type-checking/#classes-as-types

Another wonderful learning !

Excellent tutorial; thanks!

I have been using type hints for years and still learned something new in the video. Specifically, adding alias for types :)

I came to learn about duck typing stayed for the entire tutorial.

Exciting and helpful, thanks a lot! Is it possible to use type hints in single-dispatch generic functions to extend their functionality? Let’s say I need to make a @singledispatchmethod implement dispatch according to the type of a range of arguments passed into the function in a container - e.g., list or tuple:

from datetime import date
from functools import singledispatchmethod
from typing import Tuple, Dict


class BirthInfo:
    @singledispatchmethod
    def __init__(self, birth_date):
        raise ValueError(f"unsupported date format: {birth_date}")

    @__init__.register(date)
    def _from_date(self, birth_date):
        self.date = birth_dat

    @__init__.register()
    def _from_tuple_of_dicts(self, birth_date: Tuple[dict, dict, dict]):
        self.date = date(*tuple(pair[key]
                                for pair in birth_date
                                for key in pair))


dav = Person("Dav Smith", ({"year": 2000}, {"month": 7}, {"day": 25}))

Can it be done with type hints for sequence objects? Or is it better to create a custom class of some kind for it? The above example raises a TypeError: singledispatchmethod.register() missing 1 required positional argument: ‘cls’. It can be handled by passing ‘tuple’ as ‘cls’ into @init.register(tuple), but I am curious if it can be done just with type hints?