Builder

Builder Design Pattern
用在Java的Thrad其Runnable介面即是利用Builder Design
寫Java其實你已經跟著他的步驟在使用Pattern
只是渾然不覺
使用別人寫的系統時不如花點時間思考一下
為什麼別人要這樣設計?

class Ibuilder {
public:
 virtual void build(){}
};

class good_builder : public Ibuilder {
public:
 virtual void build()
 {
  cout << "good building\n";
 }
};

class bad_builder : public Ibuilder {
public:
 virtual void build()
 {
  cout << "bad building\n";
 }
};

class who_use_builder : public Ibuilder {
private:
 Ibuilder *builder;
public:
 who_use_builder(Ibuilder *builder)
 {
  this->builder = builder;
 }

 who_use_builder()
 {
  this->builder = this;
 }

 virtual void build()
 {
 
 }

 void start_build()
 {
  this->builder->build();
 }
};

class I_use_builder : public who_use_builder {
public:
 virtual void build()
 {
  cout << "fair building\n";
 }
};

int main()
{
 // like extends Thread
 I_use_builder* me = new I_use_builder();
 me->start_build();
 // like implements Runnable interface
 who_use_builder* w1 = new who_use_builder(new good_builder);
 w1->start_build();
 
 who_use_builder* w2 = new who_use_builder(new bad_builder);
 w2->start_build();
 
 return 0;
}