4 ms·

Good list, its one of these things you either never heard of, or used for years and think everyone knew that. I'll add a few: * did you know init.py is opt

Good list, its one of these things you either never heard of, or used for years and think everyone knew that. I'll add a few: * 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() anyone know more things?

zahlman 2y ago
> did you know __init__.py is optional nowadays? It has an effect, and is usually worth including anyway. I used to omit it by default; now I include it by default. Also, you say "nowadays" but it's been almost 13 years now (https://peps.python.org/pep-0420/ https://peps.python.org/pep-0420/). > since 3.13 there is a @deprecated decorator that does what you think it does Nice find. Probably worth mentioning it comes from the `warnings` standard library. > the time package has functions for monotonic clocks and others not just time() There's quite a bit in there, but I question how many people need it. Anyway, it's always surprising to me how when other people make these lists, such a large fraction is taken up by tricks with type annotations. I was skeptical of the functionality when the `typing` standard library was introduced; I've only grown more and more wary of it, even as people continue to insist to me that it's somehow necessary.
- lyu07282 2y ago
  do you know any other things you can think of that people might not be aware of? small tricks or some such, perhaps unrelated to type annotations?
  - zahlman 2y ago
    I wouldn't really know what to count in that category. I usually think more about a) really beginner-level issues (and trying to figure out why they trip up beginners, and how best to teach them in detail) and b) making my own code more beautiful (a zen-like practice that mostly defies being reduced to a tips-and-tricks list).
globular-toast 2y ago
> did you know __init__.py is optional nowadays? It's not optional. Omitting it gets you a namespace package, which is probably not what you want. > TypeVar supports binding to enforce subtypes: "TypeVar['T', bound=X]", Using the new generics syntax you mentioned above you can now do: def method[T: X](...)
- lyu07282 2y ago
  good points! do you have any more things along those lines you think people might not know about?

Good list, its one of these things you either never heard of, or used for years and think everyone knew that. I'll add a few: * did you know __init__.py is opt

zahlman 2y ago

> did you know __init__.py is optional nowadays? It has an effect, and is usually worth including anyway. I used to omit it by default; now I include it by default. Also, you say "nowadays" but it's been almost 13 years now (https://peps.python.org/pep-0420/ https://peps.python.org/pep-0420/). > since 3.13 there is a @deprecated decorator that does what you think it does Nice find. Probably worth mentioning it comes from the `warnings` standard library. > the time package has functions for monotonic clocks and others not just time() There's quite a bit in there, but I question how many people need it. Anyway, it's always surprising to me how when other people make these lists, such a large fraction is taken up by tricks with type annotations. I was skeptical of the functionality when the `typing` standard library was introduced; I've only grown more and more wary of it, even as people continue to insist to me that it's somehow necessary.

lyu07282 2y ago
do you know any other things you can think of that people might not be aware of? small tricks or some such, perhaps unrelated to type annotations?
- zahlman 2y ago
  I wouldn't really know what to count in that category. I usually think more about a) really beginner-level issues (and trying to figure out why they trip up beginners, and how best to teach them in detail) and b) making my own code more beautiful (a zen-like practice that mostly defies being reduced to a tips-and-tricks list).

globular-toast 2y ago

> did you know __init__.py is optional nowadays? It's not optional. Omitting it gets you a namespace package, which is probably not what you want. > TypeVar supports binding to enforce subtypes: "TypeVar['T', bound=X]", Using the new generics syntax you mentioned above you can now do: def method[T: X](...)

lyu07282 2y ago
good points! do you have any more things along those lines you think people might not know about?