簡單工廠模式 C++實現

#include<iostream>
#include<string>
#include<cstdlib>
using namespace std;
/*
 簡單工廠模式實現簡單計算器程序 
 
*/
class super_compute   //抽象產品角色 
{
  private:
        int a;
        int b;
        
  public:
        void set_a(int value)
        {a = value;}    
        void set_b(int value)
        {b = value;}
        int get_a()
        {
          return a;    
        }
        
        int get_b()
        {
          return b;    
        }
        virtual int get_result()  //動態綁定條件1 
        {
          double result = 0;
          return result;
        }
       
      super_compute& operator= (const super_compute& rhs)
      {
            a = rhs.a;
            b = rhs.b;
            
            return *this;
      }  
        
    
};

/* 具體產品角色*/

class add_operator: public super_compute
{
  public:
   add_operator(int a, int b)
   {
     set_a(b);
     set_b(b);     
   }
    int get_result()
    { 
      return get_a() + get_b();
       
    }
    
};

class sub_operator: public super_compute
{  public:
   sub_operator(int a, int b)
   {
     set_a(b);
     set_b(b);     
   }
   
   int get_result()
   {
     return get_a() - get_b();     
   }    
    
};

class muti_operator: public super_compute
{  public:
   muti_operator(int a, int b)
   {
     set_a(b);
     set_b(b);     
   }
    
    int get_result()
    {
      return get_a()*get_b();    
    }
    
};

class div_operator: public super_compute
{  public:
   div_operator(int a, int b)
   {
     set_a(b);
     set_b(b);     
   }  
   
   int get_result()
   {
     return get_a()/get_b();     
   }
    
};

/*生產者角色*/
class factory
{ public:
  void creat_operator(int a, int b, char op)
  {
    super_compute *ob;            //動態綁定 
    
    switch(op)
    {
      case '+':
            ob = new add_operator(a,b);
            
            break;  
      case '-':
            ob = new sub_operator(a,b);
            break;
      case '*':
            ob = new muti_operator(a,b);
            break;
      case '/':
            ob = new div_operator(a,b);
            break;
      default:
            cout << "operator erro , please check."<< endl; 
    } 
    
    cout << "The result is "<<ob->get_result()<< endl;      //動態綁定條件2 
    
  }
};

int main()
{
  long int a,b,result;
  char op;
  
  cout << " Input the first number :"<< endl;
  cin >> a;
  cout << "Input the operator:"<< endl;
  cin >> op;
  cout << "Input the second number :" << endl; 
  cin >> b;
  factory fac;
  fac.creat_operator(a,b,op);
  system("pause");
  return 0;    
}
總結：oo的精髓是可複用、易維護和可擴展。知道了OCP原則。

C++ 動態綁定的條件 1、只有指定爲虛函數的成員函數才能進行動態綁定 2、必須通過基類類型的引用或指針才能進行函數調用。詳解見《C++primer》中文版 P479。

參考了《大話設計模式》。