gistfile1.txt

#include <map>
#include <string>
#include <iostream>

namespace MyNameSpace {
class Base
{
public:
    virtual char* GetName() const = 0;
};

class FactoryBase
{
public:
    virtual Base *Create() = 0;
};

static std::map<std::string, FactoryBase *> factoryMap;


#define CREATE_FACTORY(TypeName) \
class Factory##TypeName : public FactoryBase \
{							\
public:						\
Factory##TypeName()		\
{						\
    factoryMap[#TypeName] = this;\
}						\
virtual Base *Create()  \
{						\
return new TypeName;\
}						\
}__##TypeName;


class MainClass {
public:
    void doSomething () {
        FactoryBase *pFBase = factoryMap["B"];
        Base *pBase = pFBase->Create();

        std::cout << pBase->GetName() << std::endl;
    }
public:
    class A : public Base
    {
    public:
        virtual char *GetName() const
        {
            return "A";
        }
    };

    class B : public Base
    {
    public:
        virtual char *GetName() const
        {
            return "B";
        }
    };

    CREATE_FACTORY(A)
    CREATE_FACTORY(B)
};
}
int main()
{
    MyNameSpace::MainClass m;

    m.doSomething();

    return 0;
}