工厂模式，根据ID创建对应的实例类

//
//  main.cpp
//  TestCPP1
//
//  Created by bianchx on 15/4/27.
//  Copyright (c) 2015年 bianchx. All rights reserved.
//
 
#include <iostream>
#include <map>
 
class BaseClass
{
public:
    virtual void print()
    {
        std::cout << __FUNCTION__ << std::endl;
    }
};
 
 
typedef BaseClass *(*CreateBase)();
 
static std::map<long, CreateBase> _map;
 
class Factory
{
public:
     
    static BaseClass *createInstanse(long id)
    {
        return _map.find(id)->second();
    }
};
 
template <typename T>
struct ClassRegister:BaseClass {
    ClassRegister(long _id)
    {
        _map[_id] = &(ClassRegister::createT);
    }
     
    static BaseClass* createT()
    {
        return new T();
    }
};
 
class ClassA:public BaseClass
{
public:
    static ClassRegister<ClassA> reg;
     
    virtual void print()
    {
        std::cout << "ClassA" << std::endl;
    }
};
 
ClassRegister<ClassA> ClassA::reg(1);
 
class ClassB:public BaseClass
{
private:
    static ClassRegister<ClassB> reg;
public:
    virtual void print()
    {
        std::cout << "ClassB" << std::endl;
    }
};
 
ClassRegister<ClassB> ClassB::reg(2);
 
 
int main(int argc, const char * argv[]) {
     
    Factory::createInstanse(1)->print();
    Factory::createInstanse(2)->print();
     
    return 0;
}