구조패턴-Decorator

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[Decorator]
의도:
객체에 동적으로 새로운 서비스를 추가할 수 있게 한다. Decorator패턴은 기능의 추가를
위해서 서브클래스를 생성하는 것보다 융통성 있는 방법을 제공한다.

다른 이름:
Wrapper
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/////////////////////////////////////////////////////////////////////////////
//
// A Structural part of GoF's Design Patterns
//
// - Decorator
//
/////////////////////////////////////////////////////////////////////////////
#include <windows.h>
#include <tchar.h>

#include <iostream>
#include <memory>

/////////////////////////////////////////////////////////////////////////////
//
// Decorator
//
//
/////////////////////////////////////////////////////////////////////////////
class Component
{
public:
 virtual ~Component() {}

public:
 virtual void Operation (void) = 0;
};

class ConcreteComponent : public Component
{
public:
 virtual void Operation (void)
 {
  std::cout << "ConcreteComponent::Operation()" << std::endl;
 }
};

class Decorator : public Component
{
public:
 explicit Decorator (Component* p) :
  Component_(p)
 {
 }

public:
 virtual void Operation (void)
 {
  if (Component_.get())
   Component_->Operation ();
 }

private:
 std::auto_ptr<Component> Component_;
};

class ConcreteDecoratorA : public Decorator
{
public:
 explicit ConcreteDecoratorA (Component* p) :
  Decorator(p)
 {
 }

public:
 virtual void Operation (void)
 {
  Decorator::Operation();
  std::cout << "ConcreteDecoratorA::Operation()" << std::endl;
 }
};

class ConcreteDecoratorB : public Decorator
{
public:
 explicit ConcreteDecoratorB (Component* p) :
  Decorator(p)
 {
 }
public:
 virtual void Operation (void)
 {
  Decorator::Operation();
  std::cout << "ConcreteDecoratorB::Operation()" << std::endl;
 }
};

/////////////////////////////////////////////////////////////////////////////
//
// Startup
//
//
/////////////////////////////////////////////////////////////////////////////
int _tmain(int argc, _TCHAR* argv[])
{
 std::auto_ptr<Component> p;
 
 p.reset( new ConcreteDecoratorB (
              new ConcreteDecoratorA (
                  new ConcreteComponent())) );

 p->Operation ();

 return 0;
}
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ConcreteComponent::Operation()
ConcreteDecoratorA::Operation()
ConcreteDecoratorB::Operation()