typing the untype-able with mypy plugins (advanced) anthony explains  

Great job explaining what's going on.

Very very interesting topic. I’m using this to implement a plugin for factoryboy type annotations (types-factoryboy). It’d be great to have more videos like this explaining how to write mypy plugins, as there is very little “digested” information available, only “just read what others did” kind of documentation.

I love your videos. You have a calm presence, easy to understand and very informative. I really appreciate your content. I’ve been programming with python since 2 became three. Before that it was Java and c. I was wondering if you do any C or object pascal videos?

It's so funny that a Typing video is full of typos: P

Love this, thanks Anthony!

he is back!

there are various approaches for creating sentinels. the one with enum, but also `MISSING = type("_MISSING", (), {})()` or creating a custom class with the class keyword and then reusing a single instance of it is what I tend to use if I don't want `object()`. or even importing MISSING from dataclasses could work, but well. I'm not sure it's a good idea. everything depends whether you need concrete unions or a killer type "object" in a variable (or, more often, a parameter).

I'd be curious to hear your thoughts on how you expect/hope the type system evolves to _hopefully_ support concepts like proxy objects without the need for a plugin. Type annotations are definitely a big improvement when interacting with an existing codebase, but it still feels like a different language. The model I think of is TypeScript where there's reasonable support for type-level computations. But JS exposes far fewer implementation details, so it seems simpler to implement a type system that captures common forms of "dynamism" in JS. TS definitely has significant deficiencies (e.g. bivariant method arguments) but it seems like there may still be a lot of ideas that python could draw to be able to fully annotate a larger variety of constructs.

Class LazySingleton

For the singleton field `Lazy._inst`, my first idea would've just been to store `None` and type as `Optional[R]`. Is there a benefit to using the specific `empty` object with the _EmptyType enum instead? Related timestamp: 1:14 for creating empty object, 14:10 for updating with enum type

Why is this guy using nano wtf?

RU-vid algorithm likez me 😂

So there is no python built in way to handle that?

I didn't know that mypy plugins was a thing

Great as always

5:46 true programmer, 10:42am is early in the morning