PEP 673 –– Self Type was accepted into Python

I have yet to read the whole PEP, and I haven't written any serious Python, either, but I find this to be very well written.

It uses a simple example of a "Circle" class, a subclass of "Shape":

    class Shape:
    def set_scale(self, scale: float) -> Shape:
        self.scale = scale
        return self

    Shape().set_scale(0.5)  # => Shape
    

    class Circle(Shape):
    def set_radius(self, r: float) -> Circle:
        self.radius = r
        return self

    Circle().set_scale(0.5)  # *Shape*, not Circle
    Circle().set_scale(0.5).set_radius(2.7)
    # => Error: Shape has no attribute set_radius

The error occurs because right now, Python cannot see that `self` is a `Circle`.

This PEP fixes that.

Python type hints are becoming easier to use every day. They started really terrible, but now with "|" and list/set/dict[] most common use cases are covered.

Now I would love to iter[] replace typing.Iterable[], callable[] replace typing.Callable[], and a shortcut for Annotated (maybe & ?).

I’ve often wished Java had this exact feature (although I suppose in Java it would be called “this type” instead)