Factory Method

// design_pattern_factory.cpp : Defines the entry point for the console application.//#include "stdafx.h"class Product{};//-----------------------------------------------------------------------------//first implementationtypedef int ProductId;const int MINE= 1;const int YOURS= 2;const int THEIRS= 3;class MyProduct : public Product{int my;};class YourProduct : public Product{int your;};class TheirProduct : public Product{int their;};class Creater{public:virtual Product* Create(ProductId);};Product* Creater::Create(ProductId id){if(MINE == id){return new MyProduct;}if(YOURS == id){return new YourProduct;}if(THEIRS == id){return new TheirProduct;}//repeat for remaining products...//...return 0;}class MyCreater : public Creater{public:virtual Product* Create(ProductId);};Product* MyCreater::Create(ProductId id){//switched YOURS and MINEif(MINE == id){return new YourProduct;}if(YOURS == id){return new MyProduct;}if(THEIRS == id){return new TheirProduct;}return Creater::Create(id);}//-----------------------------------------------------------------------------//second implementationclass Creater2{public:Product* GetProduct();virtual Product* CreateProduct(){return new Product;}private:Product*m_Product;};Product* Creater2::GetProduct(){if(0 == m_Product){m_Product = CreateProduct();}return m_Product;}class MyCreater2 : public Creater2{public:Product* CreateProduct();};Product* MyCreater2::CreateProduct(){return new MyProduct;}//-----------------------------------------------------------------------------//third implementationclass Creater3{public:virtual ~Creater3() {}virtual Product* CreateProduct() = 0;};template <class TheProduct>class StandardCreator: public Creater3 {public: virtual Product* CreateProduct();};template <class TheProduct>Product* StandardCreator<TheProduct>::CreateProduct(){return new TheProduct;}class MyProduct3 : public Product{public:MyProduct3(){}private:int my3;};int _tmain(int argc, _TCHAR* argv[]){//test first implementationMyCreater my_creater;Product* pProduct = my_creater.Create(1);MyProduct* pMyProduct = (MyProduct*)my_creater.Create(MINE);YourProduct* pYourProduct = (YourProduct*)my_creater.Create(MINE);//test second implementation//...MyCreater2myCreate2;MyProduct* pMyProduct2 = (MyProduct*)myCreate2.GetProduct();//test third implementationStandardCreator<MyProduct3> myCreator3;MyProduct3* myproduct3 = (MyProduct3*)myCreator3.CreateProduct();StandardCreator<YourProduct> yourCreator3;YourProduct* yourproduct3 = (YourProduct*)yourCreator3.CreateProduct();return 0;} 

 

//example used in tlbb//-----------------------------------------------------------------------------class Packet{};class PacketFactory {public :virtual ~PacketFactory () {}virtual Packet*CreatePacket () = 0;virtual PacketID_tGetPacketID ()const = 0;virtual UINTGetPacketMaxSize ()const = 0;};class GCChat : public Packet {};class GCChatFactory : public PacketFactory {public:Packet*CreatePacket() { return new GCChat() ; }PacketID_tGetPacketID() const { return PACKET_GC_CHAT ; }UINTGetPacketMaxSize()const { return sizeof(BYTE) + sizeof(CHAR)*MAX_CHAT_SIZE; }};class PacketFactoryManager {public :PacketFactoryManager( ) ;~PacketFactoryManager( ) ;private :VOIDAddFactory( PacketFactory* pFactory ) ;public :BOOLInit( ) ;Packet*CreatePacket( PacketID_t packetID ) ;UINTGetPacketMaxSize( PacketID_t packetID ) ;VOIDRemovePacket( Packet* pPacket ) ;VOIDLock( ){ m_Lock.Lock() ; } ;VOIDUnlock( ){ m_Lock.Unlock() ; } ;private :PacketFactory **m_Factories ;USHORTm_Size ;public :UINT*m_pPacketAllocCount ;};//-----------------------------------------------------------------------------