본문으로 이동

데코레이터 패턴

위키백과, 우리 모두의 백과사전.
Cedar101 (토론 | 기여)님의 2009년 1월 9일 (금) 11:38 판 ({{토막글|전산학}})

데코레이터 패턴'(Decorator pattern)이란 주어진 상황 및 용도에 따라 어떤 객체에 책임을 덧붙이는 패턴으로, 기능 확장이 필요할 때 서브클래싱 대신 쓸 수 있는 유연한 대안이 될 수 있다.

예

자바

// the Window interface
interface Window {
    public void draw(); // draws the Window
    public String getDescription(); // returns a description of the Window
}


// implementation of a simple Window without any scrollbars
class SimpleWindow implements Window {
    public void draw() {
        // draw window
    }

    public String getDescription() {
        return "simple window";
    }
}

아래의 클래스들은 모든 Window 클래스들의 데코레이터를 포함하고 있다. 

// abstract decorator class - note that it implements Window
abstract class WindowDecorator implements Window {
    protected Window decoratedWindow; // the Window being decorated

    public WindowDecorator (Window decoratedWindow) {
        this.decoratedWindow = decoratedWindow;
    }
}


// the first concrete decorator which adds vertical scrollbar functionality
class VerticalScrollBarDecorator extends WindowDecorator {
    public VerticalScrollBarDecorator (Window decoratedWindow) {
        super(decoratedWindow);
    }
 
    public void draw() {
        drawVerticalScrollBar();
        decoratedWindow.draw();
    }

    private void drawVerticalScrollBar() {
        // draw the vertical scrollbar
    }

    public String getDescription() {
        return decoratedWindow.getDescription() + ", including vertical scrollbars";
    }
}


// the second concrete decorator which adds horizontal scrollbar functionality
class HorizontalScrollBarDecorator extends WindowDecorator {
    public HorizontalScrollBarDecorator (Window decoratedWindow) {
        super(decoratedWindow);
    }

    public void draw() {
        drawHorizontalScrollBar();
        decoratedWindow.draw();
    }

    private void drawHorizontalScrollBar() {
        // draw the horizontal scrollbar
    }

    public String getDescription() {
        return decoratedWindow.getDescription() + ", including horizontal scrollbars";
    }
}

Window 인스터스를 만드는 테스트 프로그램은 아래와 같다. 

public class DecoratedWindowTest {
    public static void main(String[] args) {
        // create a decorated Window with horizontal and vertical scrollbars
        Window decoratedWindow = new HorizontalScrollBarDecorator (
                new VerticalScrollBarDecorator(new SimpleWindow()));

        // print the Window's description
        System.out.println(decoratedWindow.getDescription());
    }
}

C++

#include <iostream>

using namespace std;

/* Component (interface) */
class Widget {

public: 
  virtual void draw() = 0; 
  virtual ~Widget() {}
};  

/* ConcreteComponent */
class TextField : public Widget {

private:                  
   int width, height;

public:
   TextField( int w, int h ){ 
      width  = w;
      height = h; 
   }
   
   void draw() { 
      cout << "TextField: " << width << ", " << height << '\n'; 
   }
};

/* Decorator (interface) */                                           
class Decorator : public Widget {

private:
   Widget* wid;       // reference to Widget
                                  
public:
   Decorator( Widget* w )  { 
     wid = w; 
   }

   void draw() { 
     wid->draw(); 
   }

   ~Decorator() {
     delete wid;
   }
};

/* ConcreteDecoratorA */
class BorderDecorator : public Decorator { 

public:
   BorderDecorator( Widget* w ) : Decorator( w ) { }
   void draw() {
      Decorator::draw();    
      cout << "   BorderDecorator" << '\n'; 
   }  
};

/* ConcreteDecoratorB */
class ScrollDecorator : public Decorator { 
public:
   ScrollDecorator( Widget* w ) : Decorator( w ) { }
   void draw() {
      Decorator::draw(); 
      cout << "   ScrollDecorator" << '\n';
   }  
};

int main( void ) {
   
   Widget* aWidget = new BorderDecorator(
                     new ScrollDecorator(
                     new TextField( 80, 24 )));
   aWidget->draw();
   delete aWidget;
}

C#

namespace GSL_Decorator_pattern
{
	interface IWindowObject
	{
		void draw(); // draws the object
		String getDescription(); // returns a description of the object
	}


	class ControlComponent : IWindowObject
	{
		public ControlComponent()
		{
		}

		public void draw() // draws the object
		{
			Console.WriteLine( "ControlComponent::draw()" ); 
		}

		public String getDescription() // returns a description of the object
		{
			return "ControlComponent::getDescription()";
		}
	}

	abstract class Decorator : IWindowObject
	{
		protected IWindowObject _decoratedWindow = null; // the object being decorated

		public Decorator( IWindowObject decoratedWindow )
		{
			_decoratedWindow = decoratedWindow;
		}

		public virtual void draw()
		{
			_decoratedWindow.draw();
			Console.WriteLine("\tDecorator::draw() ");
		}

		public virtual String getDescription() // returns a description of the object
		{
			return _decoratedWindow.getDescription() + "\n\t" + "Decorator::getDescription() ";
		}
	}

	// the first decorator 
	class DecorationA : Decorator
	{
		public DecorationA(IWindowObject decoratedWindow) : base(decoratedWindow)
		{
		}

		public override void draw()
		{
			base.draw();
			DecorationAStuff();
		}

		private void DecorationAStuff()
		{
			Console.WriteLine("\t\tdoing DecorationA things");
		}

		public override String getDescription()
		{
			return base.getDescription() + "\n\t\tincluding " + this.ToString();
		}

	}// end  class ConcreteDecoratorA : Decorator

	class DecorationB : Decorator
	{
		public DecorationB(IWindowObject decoratedWindow) : base(decoratedWindow)
		{
		}

		public override void draw()
		{
			base.draw();
			DecorationBStuff();
		}

		private void DecorationBStuff()
		{
			Console.WriteLine("\t\tdoing DecorationB things");
		}

		public override String getDescription()
		{
			return base.getDescription() + "\n\t\tincluding " + this.ToString();
		}

	}// end  class DecorationB : Decorator

	class DecorationC : Decorator
	{
		public DecorationC(IWindowObject decoratedWindow) : base(decoratedWindow)
		{
		}

		public override void draw()
		{
			base.draw();
			DecorationCStuff();
		}

		private void DecorationCStuff()
		{
			Console.WriteLine("\t\tdoing DecorationC things");
		}

		public override String getDescription()
		{
			return base.getDescription() + "\n\t\tincluding " + this.ToString();
		}

	}// end  class DecorationC : Decorator

}// end of namespace GSL_Decorator_pattern

파이썬

class Coffee:
    def cost(self):
        return 1

class Milk:
    def __init__(self, coffee):
        self.coffee = coffee

    def cost(self):
        return self.coffee.cost() + .5

class Whip:
    def __init__(self, coffee):
        self.coffee = coffee

    def cost(self):
        return self.coffee.cost() + .7

class Sprinkles:
    def __init__(self, coffee):
        self.coffee = coffee

    def cost(self):
        return self.coffee.cost() + .2

# Example 1
coffee = Milk(Coffee())
print "Coffee with milk : "+str(coffee.cost())

# Example 2
coffee = Whip(Milk(Sprinkles(Coffee())))
print "Coffee with milk, whip and sprinkles : "+str(coffee.cost())

자바스크립트 커피숍

//Class to be decorated
function Coffee(){
    this.cost = function(){
	return 1;
    };
}

//Decorator A
function Milk(coffee){
    this.cost = function(){
	return coffee.cost() + 0.5;
    };	
}

//Decorator B
function Whip(coffee){
    this.cost = function(){
	return coffee.cost() + 0.7;
    };
}

//Decorator C
function Sprinkles(coffee){
    this.cost = function(){
	return coffee.cost() + 0.2;
    };
}

//Here's one way of using it
var coffee = new Milk(new Whip(new Sprinkles(new Coffee())));
alert( coffee.cost() );

//Here's another
var coffee = new Coffee();
coffee = new Sprinkles(coffee);
coffee = new Whip(coffee);
coffee = new Milk(coffee);
alert(coffee.cost());
이 토막글 틀의 변수는 잘못 사용되었습니다. 알맞은 변수를 토막글 모음에서 골라 사용해 주세요.
원본 주소 "https://ko.wikipedia.org/w/index.php?title=데코레이터_패턴&oldid=2724907"