====== Builder 패턴 ======

===== 타입 =====
Creational Pattern

===== 문제 =====
복잡한 객체를 생성하고 싶다. 그러나 인수가 많은 생성자를 쓰고 싶지는 않다.

===== 해결 =====
원하는 객체만 정의하는 멤버 함수를 가지는 중간 클래스를  정의한다.\\
그리고 중간 클래스 여러개를 조합하여 클라이언트가 원하는 객체를 만드는 최종 클래스를 정의한다.

===== 클래스 다이어그램 =====
{{:programming:design_pattern:builder.png|}}

===== 예제 =====

<file cpp builder.cpp>
#include <string>
#include <iostream>
  
using namespace std;
  
// "Product"
class Pizza
{
        public:
                void setDough(const string& dough)
                {
                        m_dough = dough;
                }
                void setSauce(const string& sauce)
                {
                        m_sauce = sauce;
                }
                void setTopping(const string& topping)
                {
                        m_topping = topping;
                }
                void open() const
                {
                        cout << "Pizza with " << m_dough << " dough, " << m_sauce << " sauce and "
                        << m_topping << " topping. Mmm." << endl;
                }
        private:
                string m_dough;
                string m_sauce;
                string m_topping;
};
  
// "Abstract Builder"
class PizzaBuilder
{
        public:
                Pizza* getPizza()
                {
                        return m_pizza;
                }
                void createNewPizzaProduct()
                {
                        m_pizza = new Pizza;
                }
                virtual void buildDough() = 0;
                virtual void buildSauce() = 0;
                virtual void buildTopping() = 0;
        protected:
                Pizza* m_pizza;
};
  
//----------------------------------------------------------------
  
class HawaiianPizzaBuilder : public PizzaBuilder
{
        public:
                virtual void buildDough()
                {
                        m_pizza->setDough("cross");
                }
                virtual void buildSauce()
                {
                        m_pizza->setSauce("mild");
                }
                virtual void buildTopping()
                {
                        m_pizza->setTopping("ham+pineapple");
                }
};
  
class SpicyPizzaBuilder : public PizzaBuilder
{
        public:
                virtual void buildDough()
                {
                        m_pizza->setDough("pan baked");
                }
                virtual void buildSauce()
                {
                        m_pizza->setSauce("hot");
                }
                virtual void buildTopping()
                {
                        m_pizza->setTopping("pepperoni+salami");
                }
};
  
//----------------------------------------------------------------
  
class Cook
{
        public:
                void setPizzaBuilder(PizzaBuilder* pb)
                {
                        m_pizzaBuilder = pb;
                }
                Pizza* getPizza()
                {
                        return m_pizzaBuilder->getPizza();
                }
                void constructPizza()
                {
                        m_pizzaBuilder->createNewPizzaProduct();
                        m_pizzaBuilder->buildDough();
                        m_pizzaBuilder->buildSauce();
                        m_pizzaBuilder->buildTopping();
                }
        private:
                PizzaBuilder* m_pizzaBuilder;
};
  
int main()
{
        Cook cook;
        PizzaBuilder* hawaiianPizzaBuilder = new HawaiianPizzaBuilder;
        PizzaBuilder* spicyPizzaBuilder   = new SpicyPizzaBuilder;
  
        cook.setPizzaBuilder(hawaiianPizzaBuilder);
        cook.constructPizza();
  
        Pizza* hawaiian = cook.getPizza();
        hawaiian->open();
  
        cook.setPizzaBuilder(spicyPizzaBuilder);
        cook.constructPizza();
  
        Pizza* spicy = cook.getPizza();
        spicy->open();
  
        delete hawaiianPizzaBuilder;
        delete spicyPizzaBuilder;
        delete hawaiian;  
        delete spicy;

        return 0;
}
</file>

===== 참고 =====
http://en.wikibooks.org/wiki/C%2B%2B_Programming/Code/Design_Patterns#Builder