Python type hints: статическая типизация

1# Без type hints
2def add(a, b):
3    return a + b
4
5# С type hints
6def add(a: int, b: int) -> int:
7    return a + b

1name: str = "Alice"
2age: int = 25
3height: float = 1.75
4is_active: bool = True

1from typing import List, Dict, Tuple, Set, Optional
2
3# Списки
4numbers: List[int] = [1, 2, 3]
5names: list[str] = ["Alice", "Bob"]  # Python 3.9+
6
7# Словари
8user: Dict[str, int] = {"age": 25}
9scores: dict[str, float] = {"math": 95.5}  # Python 3.9+
10
11# Кортежи
12point: Tuple[int, int] = (10, 20)
13point: tuple[int, int] = (10, 20)  # Python 3.9+
14
15# Множества
16unique: Set[int] = {1, 2, 3}
17
18# Опциональные значения
19name: Optional[str] = None  # str | None

1from typing import Union, Literal
2
3# Union — одно из типов
4value: Union[int, str] = 42
5value: int | str = 42  # Python 3.10+
6
7# Literal — конкретные значения
8status: Literal["active", "inactive", "pending"] = "active"

1def greet(name: str) -> str:
2    return f"Hello, {name}"
3
4def process(data: list[int], factor: float = 1.0) -> list[float]:
5    return [x * factor for x in data]

1from typing import Callable
2
3def apply(func: Callable[[int, int], int], a: int, b: int) -> int:
4    return func(a, b)
5
6def add(a: int, b: int) -> int:
7    return a + b
8
9result = apply(add, 2, 3)  # 5

1from typing import TypeVar, Generic
2
3T = TypeVar('T')
4
5class Stack(Generic[T]):
6    def __init__(self) -> None:
7        self.items: list[T] = []
8
9    def push(self, item: T) -> None:
10        self.items.append(item)
11
12    def pop(self) -> T:
13        return self.items.pop()
14
15# Использование
16int_stack: Stack[int] = Stack()
17int_stack.push(42)

1from typing import TypeVar
2
3T = TypeVar('T', int, float)
4
5def sum_values(values: list[T]) -> T:
6    return sum(values)  # type: ignore
7
8sum_values([1, 2, 3])      # OK
9sum_values([1.0, 2.0])     # OK
10sum_values(["a", "b"])     # Ошибка!

1from typing import Protocol
2
3class Drawable(Protocol):
4    def draw(self) -> None: ...
5
6class Circle:
7    def draw(self) -> None:
8        print("Drawing circle")
9
10class Square:
11    def draw(self) -> None:
12        print("Drawing square")
13
14def draw_shape(shape: Drawable) -> None:
15    shape.draw()
16
17draw_shape(Circle())  # OK
18draw_shape(Square())  # OK

1from typing import TypedDict
2
3class UserDict(TypedDict):
4    name: str
5    age: int
6    email: str
7
8def process_user(user: UserDict) -> str:
9    return f"{user['name']} ({user['age']})"
10
11# Использование
12user: UserDict = {
13    "name": "Alice",
14    "age": 25,
15    "email": "alice@test.com"
16}

1pip install mypy
2
3# Проверка файла
4mypy script.py
5
6# Проверка проекта
7mypy src/

1[mypy]
2python_version = 3.11
3strict = True
4warn_return_any = True
5warn_unused_configs = True
6
7[mypy-third_party_lib.*]
8ignore_missing_imports = True

1result = some_untyped_function()  # type: ignore
2
3# Или на уровне модуля
4# mypy: ignore-errors

1from typing import Callable, Awaitable
2
3# Синхронная функция
4handler: Callable[[str, int], str] = lambda name, age: f"{name}: {age}"
5
6# Асинхронная функция
7async_handler: Callable[[str], Awaitable[str]] = async_lambda name: f"Hello, {name}"

1# Начните с функций
2def process(data: list[int]) -> list[int]:
3    return [x * 2 for x in data]
4
5# Потом добавляйте типы переменных
6result: list[int] = process([1, 2, 3])
7
8# Используйте Any как временное решение
9from typing import Any
10legacy_data: Any = get_legacy_data()

1# Type guard
2def is_string(value: object) -> bool:
3    return isinstance(value, str)
4
5def process(value: str | int) -> str:
6    if isinstance(value, str):
7        return value.upper()
8    return str(value)