LANGUAGE » PYTHON

Annotation

Last updated:
Reference:docs.python.org

Overview ​

Types ​

Primitives ​

python
from collections.abc import *
from typing import *  # Deprecated
  • Any: Any
  • Number: int float
  • String: str
  • Boolean: bool
  • List: tuple[Type] list[Type]
  • Dict: dict[Type1, Type2]
  • Set: Set FrozenSet
  • Symbol: -
  • Function: Callable[[Arg1Type, Arg2Type], ReturnType]
  • Empty: None
  • Unset: TypeVar Generic
  • Never: Never NoReturn
  • Union: | Literal Union Optional Concatenate
  • Class: Self ClassVar
  • Final: Final

Usage ​

For variables:

python
hello: str = 'Hello World'
value: int = 10
dict1: dict[str, str] = {}
ids: list[int] = [0, 1]

For functions:

python
def greeting() -> str:
    return 'Hello'

For classes:

python
class UserAccount:
    stats: ClassVar[dict[str, int]] = {}  # class variable
    damage: int = 10                      # instance variable

    def __init__(self: Self, damage: int) -> None:
        self.damage = damage

    def greet(self: Self, text: str) -> None
        print(text)

Custom types / interfaces ​

Decide which values are accepted:

python
MyBool = Literal[True, False]
WindowStates = Literal['open', 'closed', 'minimized']
PositiveOddNumbersUnderTen = Literal[1, 3, 5, 7, 9]

Generic types (like list):

python
NumberList: TypeAlias = list[int]
ObjectWithNameList: TypeAlias = list[dict['name', str]]