在 python 中使用类型别名然后将其声明为变量是个好主意吗？

Question

I am looking at code like this:

class DeckManager:

   decks: Dict[str, Any]

   def __init__(self, col: a) -> None:

        self.decks = {}

Is it correct that decks: Dict[str, Any] is specifying a Type Alias? If so then does it make sense to use: self.decks later in the code. Is that not confusing?

Answer 1

No, decks is not a type alias. It is a type-annotation. According to PEP-484 :

Type aliases are defined by simple variable assignments.

Or according to the typing documentation :

A type alias is defined by assigning the type to the alias.

So assigning to a variable anything that would be a valid type annotation is a type alias. So:

decks = Dict[str, Any]

When you use the colon, you are annotating that variable, not creating an alias:

decks: Dict[str, Any]

Would be a type alias. According to Python's type annotation conventions, you've simply annotated the decks attribute for DeckManager instances to have type Dict[str, Any] .