파이썬으로 작성된 팩토리 메서드
팩토리 메서드는 제품 객체들의 구상 클래스들을 지정하지 않고 해당 제품 객체들을 생성할 수 있도록 하는 생성 디자인 패턴입니다.
팩토리 메서드는 메서드를 정의하며, 이 메서드는 직접 생성자 호출(new 연산자)을 사용하여 객체를 생성하는 대신 객체 생성에 사용되여야 합니다. 자식 클래스들은 이 메서드를 오버라이드하여 생성될 객체들의 클래스를 변경할 수 있습니다.
다양한 팩토리 패턴들과 개념들의 차이점을 이해하지 못하셨다면 팩토리 비교를 읽어보세요.
복잡도:
인기도:
사용 사례들: 팩토리 메서드 패턴은 파이썬 코드에서 널리 사용되며 코드에 높은 수준의 유연성을 제공해야 할 때 매우 유용합니다.
식별: 팩토리 메서드는 구상 클래스들로부터 객체들을 생성하는 생성 메서드들로 인식될 수 있습니다. 구상 클래스들은 객체 생성 중에 사용되지만 팩토리 메서드들의 반환 유형은 일반적으로 추상 클래스 또는 인터페이스로 선언됩니다.
개념적인 예시
이 예시는 팩토리 메서드의 구조를 보여주고 다음 질문에 중점을 둡니다:
- 패턴은 어떤 클래스들로 구성되어 있나요?
- 이 클래스들은 어떤 역할을 하나요?
- 패턴의 요소들은 어떻게 서로 연관되어 있나요?
main.py: 개념적인 예시
from __future__ import annotations
from abc import ABC, abstractmethod
class Creator(ABC):
"""
The Creator class declares the factory method that is supposed to return an
object of a Product class. The Creator's subclasses usually provide the
implementation of this method.
"""
@abstractmethod
def factory_method(self):
"""
Note that the Creator may also provide some default implementation of
the factory method.
"""
pass
def some_operation(self) -> str:
"""
Also note that, despite its name, the Creator's primary responsibility
is not creating products. Usually, it contains some core business logic
that relies on Product objects, returned by the factory method.
Subclasses can indirectly change that business logic by overriding the
factory method and returning a different type of product from it.
"""
# Call the factory method to create a Product object.
product = self.factory_method()
# Now, use the product.
result = f"Creator: The same creator's code has just worked with {product.operation()}"
return result
"""
Concrete Creators override the factory method in order to change the resulting
product's type.
"""
class ConcreteCreator1(Creator):
"""
Note that the signature of the method still uses the abstract product type,
even though the concrete product is actually returned from the method. This
way the Creator can stay independent of concrete product classes.
"""
def factory_method(self) -> Product:
return ConcreteProduct1()
class ConcreteCreator2(Creator):
def factory_method(self) -> Product:
return ConcreteProduct2()
class Product(ABC):
"""
The Product interface declares the operations that all concrete products
must implement.
"""
@abstractmethod
def operation(self) -> str:
pass
"""
Concrete Products provide various implementations of the Product interface.
"""
class ConcreteProduct1(Product):
def operation(self) -> str:
return "{Result of the ConcreteProduct1}"
class ConcreteProduct2(Product):
def operation(self) -> str:
return "{Result of the ConcreteProduct2}"
def client_code(creator: Creator) -> None:
"""
The client code works with an instance of a concrete creator, albeit through
its base interface. As long as the client keeps working with the creator via
the base interface, you can pass it any creator's subclass.
"""
print(f"Client: I'm not aware of the creator's class, but it still works.\n"
f"{creator.some_operation()}", end="")
if __name__ == "__main__":
print("App: Launched with the ConcreteCreator1.")
client_code(ConcreteCreator1())
print("\n")
print("App: Launched with the ConcreteCreator2.")
client_code(ConcreteCreator2())
Output.txt: 실행 결과
App: Launched with the ConcreteCreator1.
Client: I'm not aware of the creator's class, but it still works.
Creator: The same creator's code has just worked with {Result of the ConcreteProduct1}
App: Launched with the ConcreteCreator2.
Client: I'm not aware of the creator's class, but it still works.
Creator: The same creator's code has just worked with {Result of the ConcreteProduct2}
