Decorator 패턴

위키백과 ― 우리 모두의 백과사전.

(Decorator pattern에서 넘어옴)

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.

목차

[편집] 예

[편집] 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());
    }
}

[편집] 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;
}

[편집] 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

[편집] 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())

[편집] 자바스크립트

//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 글은 전산학에 관한 토막글입니다. 서로의 지식을 모아 알차게 문서를 완성해 갑시다.
원본 주소 ‘http://ko.wikipedia.org/wiki/Decorator_%ED%8C%A8%ED%84%B4’