VC 之余RTTI

最新推荐文章于 2016-09-22 13:25:53 发布

dhbo

最新推荐文章于 2016-09-22 13:25:53 发布

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分类专栏：网络技术类文章标签： class pascal null attributes import struct

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有些东西能够农明白所以然，有些不能弄明白（比如：原子弹是什么蛋？）；我要做的就是把能弄明白的弄明白。别让明白的也不明白，不明白的更不明白。

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

#define AFX_DATA AFX_CORE_DATA

#ifndef AFX_CORE_DATA
#define AFX_CORE_DATA AFX_DATA_IMPORT
#define AFX_CORE_DATADEF
#endif

#ifndef AFX_DATA_IMPORT
#define AFX_DATA_IMPORT __declspec(dllimport)
#endif

#if defined(_AFXEXT) && !defined(_AFXDLL)
#define _AFXDLL
#endif

// 原来只是多了个函数

define IMPLEMENT_DYNAMIC(class_name, base_class_name) /
IMPLEMENT_RUNTIMECLASS(class_name, base_class_name, 0xFFFF, NULL)

#ifdef _AFXDLL
#define IMPLEMENT_RUNTIMECLASS(class_name, base_class_name, wSchema, pfnNew) /
CRuntimeClass* PASCAL class_name::_GetBaseClass() /
  { return RUNTIME_CLASS(base_class_name); } /
AFX_COMDAT const AFX_DATADEF CRuntimeClass class_name::class##class_name = { /
  #class_name, sizeof(class class_name), wSchema, pfnNew, /
   &class_name::_GetBaseClass, NULL }; /
CRuntimeClass* class_name::GetRuntimeClass() const /
  { return RUNTIME_CLASS(class_name); } /

#define _IMPLEMENT_RUNTIMECLASS(class_name, base_class_name, wSchema, pfnNew) /
CRuntimeClass* PASCAL class_name::_GetBaseClass() /
  { return RUNTIME_CLASS(base_class_name); } /
AFX_COMDAT AFX_DATADEF CRuntimeClass class_name::class##class_name = { /
  #class_name, sizeof(class class_name), wSchema, pfnNew, /
   &class_name::_GetBaseClass, NULL }; /
CRuntimeClass* class_name::GetRuntimeClass() const /
  { return RUNTIME_CLASS(class_name); } /

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

#define _IMPLEMENT_RUNTIMECLASS(class_name, base_class_name, wSchema, pfnNew) /
AFX_DATADEF CRuntimeClass class_name::class##class_name = { /
  #class_name, sizeof(class class_name), wSchema, pfnNew, /
   RUNTIME_CLASS(base_class_name), NULL }; /
CRuntimeClass* class_name::GetRuntimeClass() const /
  { return RUNTIME_CLASS(class_name); } /

#endif

       #define AFX_COMDAT
       #define AFX_DATADEF
       #define AFX_DATA AFX_CORE_DATA

/
// Basic object model

struct CRuntimeClass
{
// Attributes
LPCSTR m_lpszClassName;
int m_nObjectSize;
UINT m_wSchema; // schema number of the loaded class
CObject* (PASCAL* m_pfnCreateObject)(); // NULL => abstract class
#ifdef _AFXDLL
CRuntimeClass* (PASCAL* m_pfnGetBaseClass)();
#else
CRuntimeClass* m_pBaseClass;
#endif

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

// 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
};

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

在候捷的深入浅出MFC 中还有：

struct AFX_CLASSINIT
{ AFX_CLASSINIT(CRuntimeClass* pNewClass); };

这个暂时没有弄明白，在VC 中翻原代码没有翻到，我会继续查的

总之我的感觉，这是在给加了这个宏的代码中加入了一个静态成员函数，而CRuntimeClass 这个结构的建立就是一个有表头指针的单链表，方便的实现了RTTI

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2006/8/6