typing

typing 模块

typing 模块提供高级类型支持：

from typing import List, Dict, Tuple, Optional, Union

# 容器类型
names: List[str] = ["Alice", "Bob"]
person: Dict[str, Union[str, int]] = {"name": "Alice", "age": 30}

# 可选类型
def get_age(name: str) -> Optional[int]:
    if name == "Alice":
        return 30
    return None

# 类型别名
UserId = int
user_id: UserId = 1001

泛型 (Generic)

创建可复用的类型安全容器：

from typing import TypeVar, Generic, List

T = TypeVar('T')

class Stack(Generic[T]):
    def __init__(self) -> None:
        self._items: List[T] = []
    
    def push(self, item: T) -> None:
        self._items.append(item)
    
    def pop(self) -> T:
        return self._items.pop()

# 使用
int_stack: Stack[int] = Stack()
int_stack.push(42)

Literal 字面量类型

限制值只能是特定的字面量：

from typing import Literal

def set_mode(mode: Literal["read", "write", "append"]) -> None:
    print(f"Mode set to: {mode}")

set_mode("read")    # 正确
set_mode("delete")  # 类型检查器会报错

# 多种类型的字面量
def process_flag(flag: Literal[True, False, 0, 1]) -> None:
    pass