根据字符串类名动态创建对象

根据字符串类名动态创建对象

老板很无理的要求，硬是让程序能够根据给定的字符串类名来创建相应的对象，哎，为此折腾了几天！

////////////////////////reflect.h文件



#ifndef REFLECT_H

#define REFLECT_H



class ClassDef;

class __ClassDefiner;



typedef void (*ConstructObjectFn)(void *pObject);

typedef void (*DestructObjectFn)(void *pObject);



//自己重载new运算符

inline void * __cdecl operator new(unsigned int size,void* ptr,int le,char ch) 

{ 

    return ptr;

};



#define DEFINE_HANDLE_TYPE(name) /

    typedef struct TT{int __nothing;} name##_t, *name;



//类的构造函数和析构函数

#define DO_DEFAULT_FUNCTIONS(_ClassName) /

    void Default##_ClassName##Constructor(void *ptr)/

{/

    new(ptr,(int)0,(char)0) _ClassName;/

};/

    void Default##_ClassName##Destructor(void *ptr)/

{/

    _ClassName *thePtr = (_ClassName*)ptr;/

    thePtr->~_ClassName();/

};/



#define DO_AUTO_CLASSLIST(name) /

    static __ClassDefiner __##name##_definer(&_##name##_Class__);



//

#define CLASS_SYMBOL(name, parentSymbol, construct_fn, destruct_fn) /

    ClassDef _##name##_Class__ = { /

#name, #parentSymbol, /

    construct_fn, destruct_fn, /

    sizeof(name) ,/

}; /

    DO_AUTO_CLASSLIST(name) /

    __int32 __impl_instance_##name##__;                  



 





class ClassDef 

{

public:



    char *m_ClassName;

    char *m_ParentClass;



    //构造函数和析构函数

    ConstructObjectFn m_ConstructFn;

    DestructObjectFn m_DestructFn;



    // How big an object of this class is (set automatically).

    long m_ClassObjectSize;

};



class __ClassDefiner

{

public:



    __ClassDefiner(ClassDef *pDef);





    ClassDef        *m_pClass;

    __ClassDefiner  *m_pNext;



};

#define Declare(CLASSC,CLASSP)  /

    DO_DEFAULT_FUNCTIONS(CLASSC)/

    CLASS_SYMBOL(CLASSC,CLASSP,Default##CLASSC##Constructor,Default##CLASSC##Destructor)



class classMgr 

{

public:

    void* GetClassByName(char* _name);



};



#endif

 

 

///////////////////////reflect.cpp文件

#include "reflect.h"

#include <iostream>



__ClassDefiner *__g_ClassDefinerHead = NULL;





__ClassDefiner::__ClassDefiner( ClassDef *pDef )

{

    m_pClass = pDef;

    m_pNext = __g_ClassDefinerHead;

    __g_ClassDefinerHead = this;

}



void* classMgr::GetClassByName( char* _name )

{

    __ClassDefiner* cd = __g_ClassDefinerHead;

    while (cd)

    {

        if ( strcmp(cd->m_pClass->m_ClassName ,_name) == 0  )

        {

            void *p = malloc(cd->m_pClass->m_ClassObjectSize);

            cd->m_pClass->m_ConstructFn(p); 

            return p;

        }

        cd = cd->m_pNext;

    }

    return NULL;

}

////////////////////////测试程序

//////////////Base、Derived和Child为自己写的测试类，其继承关系为Derived和Child都继承于Base



///////////////////////建立类似于MFC RTTI的类型识别网

Declare(Derived,Base);

Declare(Child,Base);





int main()

{

    classMgr cm;

    Base* b=(Base *)cm.GetClassByName("Derived");

    b->DoSth();

    getchar();

    free(b);

    b=(Base *)cm.GetClassByName("Child");

    b->DoSth();

    getchar();

    return 0;

}