RTTI（CRuntimeClass结构体）

struct CRuntimeClass
{
// Attributes
 LPCSTR m_lpszClassName;                      //类名
 int m_nObjectSize;
 UINT m_wSchema; // schema number of the loaded class
 CObject* (PASCAL* m_pfnCreateObject)(); // NULL => abstract class  默认构造函数的函数指针，创建一个类的对象，抽象类则返回NULL
#ifdef _AFXDLL
 CRuntimeClass* (PASCAL* m_pfnGetBaseClass)();
#else
 CRuntimeClass* m_pBaseClass;    //基类
#endif

// Operations
 CObject* CreateObject();
 BOOL IsDerivedFrom(const CRuntimeClass* pBaseClass) const;

 // dynamic name lookup and creation
 static CRuntimeClass* PASCAL FromName(LPCSTR lpszClassName);
 static CRuntimeClass* PASCAL FromName(LPCWSTR lpszClassName);
 static CObject* PASCAL CreateObject(LPCSTR lpszClassName);
 static CObject* PASCAL CreateObject(LPCWSTR lpszClassName);

// Implementation
 void Store(CArchive& ar) const;
 static CRuntimeClass* PASCAL Load(CArchive& ar, UINT* pwSchemaNum);

 // CRuntimeClass objects linked together in simple list
 CRuntimeClass* m_pNextClass;       // linked list of registered classes    next指针
 const AFX_CLASSINIT* m_pClassInit;
};

类别型录网

 

DECLARE_DYNAMIC/IMPLEMENT_DYNAMIC宏

 

#define DECLARE_DYNAMIC(class_name) \
public: \
 static const CRuntimeClass class##class_name; \
 virtual CRuntimeClass* GetRuntimeClass() const; \

 

#define IMPLEMENT_DYNAMIC(class_name, base_class_name) \
 IMPLEMENT_RUNTIMECLASS(class_name, base_class_name, 0xFFFF, NULL, NULL)

 

#define IMPLEMENT_RUNTIMECLASS(class_name, base_class_name, wSchema, pfnNew, class_init) \
 AFX_COMDAT const CRuntimeClass class_name::class##class_name = { \
  #class_name, sizeof(class class_name), wSchema, pfnNew, \
   RUNTIME_CLASS(base_class_name), NULL, class_init }; \
 CRuntimeClass* class_name::GetRuntimeClass() const \
  { return RUNTIME_CLASS(class_name); } \

 

#define AFX_COMDAT __declspec(selectany)

#define RUNTIME_CLASS(class_name) _RUNTIME_CLASS(class_name)

 

#define _RUNTIME_CLASS(class_name) ((CRuntimeClass*)(&class_name::class##class_name))

 

 

值得注意的是：CRuntimeClass结构体的静态成员pFirstClass指针属于类，所以从一开始它就记录了所有生成的类的类别型录，整个程序中仅此一份，于是便可方便的进行IsKindOf操作。如下：

　　　　　　　

　　void PrintAllClasses()

　　{

　　　　CRuntimeClass* pClass;

　　　　for(pClass = CRuntimeClass::pFirstClass; pClass!=NULL;pClass = pClass->m_pNextClass)

　　　　{

　　　　　　cout << pClass->m_lpszClassName << "\n";

　　　　　　cout << pClass->m_nObjectSize << "\n";

　　　　　　cout << pClass->m_wSchema << "\n";

　　　　}

　　}

 

 

注意，while循环所追踪的是“同宗”路线，也就是凭借着m_pBaseClass而非m_pNextClass。