////////////////////////////////////////////////////////////////////////////////
// The Loki Library
// Copyright (c) 2001 by Andrei Alexandrescu
// This code accompanies the book:
// Alexandrescu, Andrei. Modern C++ Design: Generic Programming and Design 
//     Patterns Applied. Copyright (c) 2001. Addison-Wesley.
// Permission to use, copy, modify, distribute and sell this software for any 
//     purpose is hereby granted without fee, provided that the above copyright 
//     notice appear in all copies and that both that copyright notice and this 
//     permission notice appear in supporting documentation.
// The author or Addison-Wesley Longman make no representations about the 
//     suitability of this software for any purpose. It is provided as is 
//     without express or implied warranty.
////////////////////////////////////////////////////////////////////////////////
#ifndef LOKI_ABSTRACTFACTORY_INC_
#define LOKI_ABSTRACTFACTORY_INC_

// $Id: AbstractFactory.h 771 2006-10-27 18:05:03Z clitte_bbt $



#include HierarchyGenerators.h
#include typelists.h
#include 
  
   
#include 
   
     namespace Loki { //////////////////////////////////////////////////////////////////////////////// //Type2Type
    
      用于消除歧义，因为同一个继承体会有多个AbstractFactoryUnit的具现体 //如：AbstractFactoryUnit
      ,AbstractFactoryUnit等 //DoCreate这个函数返回的并不是一个常类型，因为T为可变的 //在c++中，你可以返回型别为Pointer to Derived class 的函数改写（overide)为“返回 // pointer to base class的函数。这个就是”协变式返回型别（covariant return types) /* class A{ public: virtual A * ff() = 0; }; class B:public A{ public: B * ff(){return this;} }; 使用： B b; */ //////////////////////////////////////////////////////////////////////////////// template 
       
         class AbstractFactoryUnit { public: virtual T* DoCreate(Type2Type
        
         ) = 0; virtual ~AbstractFactoryUnit() {} }; //////////////////////////////////////////////////////////////////////////////// // class template AbstractFactory // Defines an Abstract Factory interface starting from a typelist //////////////////////////////////////////////////////////////////////////////// template < class TList, template 
         
           class Unit = AbstractFactoryUnit > class AbstractFactory : public GenScatterHierarchy
          
            { public: typedef TList ProductList; template 
           
             T* Create() { Unit
            
             & unit = *this; return unit.DoCreate(Type2Type
             
              ()); } }; //////////////////////////////////////////////////////////////////////////////// // class template OpNewFactoryUnit // Creates an object by invoking the new operator //////////////////////////////////////////////////////////////////////////////// template 
              
                class OpNewFactoryUnit : public Base { typedef typename Base::ProductList BaseProductList; protected: typedef typename BaseProductList::Tail ProductList; public: typedef typename BaseProductList::Head AbstractProduct; ConcreteProduct* DoCreate(Type2Type
               
                ) {//AbstractProduct抽象产品，ConcreteProduct具体产品，同Soldier和SillySoldier的关系 std::cout<<基类：<
                
                 )中的AbstractProduct的顺序相反，所以需要Reverse一下 当然也可以修改OpNewFactoryUnit 而不翻转ConcreteFactory中的TList 修改成如下： typedef typename Base::ProductList BaseProductList; protected: typedef typename Reverse
                 
                  %3CBaseProductList%3E::Result::Tail>::Result ProductList; public: typedef typename Reverse
                  
                   ::Result::Head AbstractProduct; 不过这种设计不太好，因为每个Creator都要处理这种翻转情况，不如在ConcreteFactory类中一下彻底解决问题好。 */ /////