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25 Apr 2025

Advanced Python features

* did you know __init__.py is optional nowadays?

* you can do relative imports with things like "from ..other import foo"

* since 3.13 there is a @deprecated decorator that does what you think it does

* the new generics syntax also works on methods/functions: "def method[T](...)" very cool

* you can type kwargs with typeddicts and unpack: "def fn(*kwargs: Unpack[MyKwargs])"

* dataclasses (and pydantic) support immutable objects with: "class MyModel(BaseModel, frozen=True)" or "@dataclass(frozen=True)"

* class attributes on dataclasses, etc. can be defined with "MY_STATIC: ClassVar[int] = 42" this also supports abstract base classes (ABC)

* TypeVar supports binding to enforce subtypes: "TypeVar['T', bound=X]", and also a default since 3.13: "TypeVar['T', bound=X, default=int]"

* @overload is especially useful for get() methods to express that the return can't be none if the default isn't None

* instead of Union[a, b] or Optional[a] you can write "a | b" or "a | None" nowadays

* with match you can use assert_never() to ensure exhaustive matching in a "case _:" block

* typing has reveal_type() which lets mypy print the type it thinks something is

* typing's "Self" allows you to more properly annotate class method return types

* the time package has functions for monotonic clocks and others not just time()
Nel mezzo del deserto posso dire tutto quello che voglio.
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