features_python

# простейший дженерик ----------------------------------------

from typing import Generic
from typing import TypeVar

T = TypeVar('T')


class Cool(Generic[T]):
    def __init__(self):
        self._storage = []

    def put(self, something: T) -> None:
        self._storage.append(something)

    def pop(self) -> T:
        return self._storage.pop()


array: Cool[int] = Cool()
array.put(1)  # Ok
array.put('wtf')  # Expected type 'int' (matched generic type 'T'), got 'str' instead 

# простейший абстрактный базовый класс ---------------------

from abc import ABC
from abc import abstractmethod


class Parent(ABC):
    @abstractmethod
    def must_implement(self):
        """Abstract."""


class Child(Parent):
    pass


c = Child()  # TypeError: Can't instantiate abstract class Child with abstract method must_implement


# простейший протокол ---------------------

from typing import Protocol


class DoProtocol(Protocol):
    def do(self) -> int:
        pass


class SomethingInt:
    def do(self) -> int:
        return 1


class SomethingStr:
    def do(self) -> str:
        return 'sd'


def some_func(something: DoProtocol) -> None:
    print(something)


some_func(SomethingInt())  # Ok
some_func(SomethingStr())  # Expected type 'DoProtocol', got 'SomethingStr' instead