Python类型提示与静态类型检查的高级应用实例代码

from typing import TypeVar, Generic, List, Optional

# 定义类型变量
t = TypeVar('T')

# 泛型类
class Stack(Generic[T]):
    def __init__(self):
        self.items: List[T] = []
    
    def push(self, item: T) -> None:
        self.items.append(item)
    
    def pop(self) -> Optional[T]:
        if self.items:
            return self.items.pop()
        return None
    
    def peek(self) -> Optional[T]:
        if self.items:
            return self.items[-1]
        return None

# 使用泛型栈
int_stack = Stack[int]()
int_stack.push(1)
int_stack.push(2)
print(int_stack.pop())  # 2

str_stack = Stack[str]()
str_stack.push("hello")
str_stack.push("world")
print(str_stack.pop())  # "world"

from typing import Protocol, runtime_checkable

# 定义协议
@runtime_checkable
class Drawable(Protocol):
    def draw(self) -> str:
        ...

# 实现协议的类
class Circle:
    def draw(self) -> str:
        return "Drawing a circle"

class Square:
    def draw(self) -> str:
        return "Drawing a square"

# 接受协议类型的函数
def render(obj: Drawable) -> str:
    return obj.draw()

# 使用
circle = Circle()
square = Square()

print(render(circle))  # "Drawing a circle"
print(render(square))  # "Drawing a square"

# 运行时检查
print(isinstance(circle, Drawable))  # True
print(isinstance(square, Drawable))  # True

from typing import Dict, List, Tuple, Union, Optional, Literal
from typing_extensions import TypedDict

# 类型别名
UserId = int
UserName = str

# TypedDict
class User(TypedDict):
    id: UserId
    name: UserName
    email: Optional[str]

# 复杂类型
def process_users(
    users: List[User],
    filters: Dict[str, Union[str, int, bool]],
    sort_by: Literal["id", "name", "email"] = "id"
) -> Tuple[List[User], int]:
    # 处理逻辑
    filtered_users = users
    for key, value in filters.items():
        filtered_users = [user for user in filtered_users if user.get(key) == value]
    
    # 排序
    filtered_users.sort(key=lambda u: u.get(sort_by, ""))
    
    return filtered_users, len(filtered_users)

# 使用
users = [
    {"id": 1, "name": "Alice", "email": "alice@example.com"},
    {"id": 2, "name": "Bob", "email": "bob@example.com"},
    {"id": 3, "name": "Charlie", "email": None}
]

result, count = process_users(users, {"email": None}, "name")
print(f"Found {count} users: {result}")

# mypy.ini 配置文件
"""
[mypy]
python_version = 3.12
disallow_untyped_defs = True
disallow_incomplete_defs = True
disallow_untyped_decorators = True
check_untyped_defs = True
disallow_untyped_calls = True
disallow_untyped_decorators = True
no_implicit_optional = True
warn_redundant_casts = True
warn_unused_ignores = True
warn_return_any = True
warn_unreachable = True
typed_package = typing_extensions
"""

# 运行 mypy 检查
# mypy --config-file mypy.ini your_module.py