一个新的Factory，一个Creator以及它们的完美结合（二）

没有办法，我弄不明白为什么我编辑得好好的文章贴出去都变味了。给大家带来不便不能全怪我。但是故事还没讲完，无论如何我都得讲下去。我在用英文写的那个版本里（纯粹为了看看贴出去的效果）提到使用GProductCreator至少有两个原因，其中一个就是为了用于Factory模式。另外一个原因是，一个继承体系最好不要让用户自己来构造，而是将自己托管给一个对象生成器，所以它们应当把自己所有的constructor声明为private，而将这个生成器声明为自己的friend。GProductCreator正好可以充当这个角色。当然，GProductCreator的CreatePolicy参数应当由继承体系提供。 下面的代码用于对上述方法的测试： #include "stdafx.h" #include #include #include #include "Factory.h" #include "Singleton.h" using namespace std; using namespace Loki; //classes for testing.begin: class GObject { public: virtual void print() = 0; }; class GTank:public GObject { public: virtual void print(){cout<<"GTank/n";} }; class GBullet:public GObject { public: virtual void print(){cout<<"GBullet/n";} }; class GETank:public GTank { public: virtual void print(){cout<<"GETank/n";} }; //classes for testing.end. typedef unsigned long identifier_type; template struct GAbstractCreator { virtual AbstractProduct* operator()(){return 0;} }; template < class Product, class AbstructProduct = GObject, class CreatePolicy = CreateUsingNew > struct GProductCreator: public GAbstractCreator { Product* pP; AbstructProduct* operator()(){ return CreatePolicy::Create(pP);} }; //Because The Create Poily I Used Is Polymorphic, Which The Loki Factory Did Not //Suport, I Add The FactoryUsingPointer Template Class Into The Libary typedef Loki::FactoryUsingPointer > Factory1; class Test; typedef Loki::FactoryUsingPointer Factory2; typedef Factory1 /*Or Factory2*/ TheFactory; typedef Loki::SingletonHolder theFactory; //Factory Uses Like This: //if( !theFactory::Instance().Register(GEnemyTankA::get_id(), GProductCreator()) ) // throw(); void f() { //Creator Test: //the simplest using: typedef GProductCreator TheTankCreator; TheTankCreator theTankCreator; theTankCreator.operator ()() ->print(); //let's use it a little more complex: GProductCreator()()->print(); //using default template argument: GProductCreator()()->print(); //ok, the complier seems not so displeasing, it works really well, //I think should not curse ms this morning. //Factory Test: //now, let's try the Factory method: Factory1 factory1; factory1.Register(1, &theTankCreator); //ok. //Singleton Test: //try Singleton: theFactory::Instance().Register(2, &theTankCreator); theFactory::Instance().CreateObject(2)->print(); //ok. //Final Test //now, let me give the compiler a puzzle: SingletonHolder < FactoryUsingPointer< GObject, unsigned long, GAbstractCreator >//FactoryUsingPointer As The First Template Argument Of SingletonHolder. ,CreateUsingMalloc ,PhoenixSingleton >::Instance().Register(1, &GProductCreator()); //oh! not give the compiler a puzzle, but you and me! //ok,the Creation Policy, the Factory Policy with Polymorphic Creator and //the Singleton Pattern, they do work together very well, that's GREAT! //ESPECIALLY, the FactoryUsingPointer and the GProductCreator are EXCITING! } int main(int argc, char* argv[]) { try { f(); } catch(DefaultFactoryError::Exception e) { cout<