RTTI是Runtime Type Identification的缩写，中文名为“运行时类型识别”。
MFC早在编译器支持RTTI之前，就有了这种能力。我们现在要以相同的手法，在Console程序中仿真出来。我希望我的类库具备IsKindOf 的能力，能在执行期侦测到某个对象是否属于某个类，并传回TRUE 或 FALSE。以形状 Shape为例 ，我希望：
即 长方形属于“长方形类”，正方形属于“长方形类”，圆不属于“长方形类”，原因是长方形派生 正方形类。
CMyDoc 属于“CMyDoc类”，CMyDoc也属于“CDocument类”，CMyDoc也属于“CCmdTarget类” ，CMyDoc不属于“CWnd类” 。原因是CCmdTarget派生CDocument类，CDocument
派生 CMyDoc类。
同时，我希望，每一个类都能拥有这样一个CRuntimeClass 成员变量，并且最后有一定的命名规则（例如，在类名称之前冠以“class”作为它的名称），然后，经由某种手段将整个类库构建好之后，“类别型录”就能呈现如下图（2）所示的面貌：
图（2）“类别型录”的链表形式
下面，以控制台应用程序Frame3为例，模拟mfc的RTTI功能。
在案例Frame3 的cpp 文件中，有这样的操作：
IMPLEMENT_DYNAMIC(CCmdTarget,CObject) IMPLEMENT_DYNAMIC(CWinThread,CCmdTarget) IMPLEMENT_DYNAMIC(CWinApp,CWinThread) IMPLEMENT_DYNAMIC(CWnd,CCmdTarget) //其实在MFC中此句是,IMPLEMENT_DYNCREATE() IMPLEMENT_DYNAMIC(CFrameWnd,CWnd) //其实在MFC中此句是,IMPLEMENT_DYNCREATE() IMPLEMENT_DYNAMIC(CDocument,CCmdTarget) IMPLEMENT_DYNAMIC(CView,CWnd)
于是，组织出如图（3-1）所示的一张大网：
为了证明，程序中存在整个“类别型录网”。我在main函数中调用 PrintAllClasses ，把链表中的每一个元素的类名称、对象大小，以及scheme.no，打印出来。
void PrintAllClasses() //输出“类别型录网“
{
CRuntimeClass* pClass;
//just walk through the simple list of registered classes
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";
}
}
效果如下：
图（4）链表中的每一个元素的类名称、对象大小，以及scheme.no，说明存在该“类别型录网”
详细代码如下：
//mfc.h
#define BOOL int
#define TRUE 1
#define FALSE 0
#define LPCSTR LPSTR
typedef char* LPSTR;
#define UINT int
#define PASCAL _stdcall
#include <iostream.h>
class CObject;
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
CRuntimeClass* m_pBaseClass;
// CRuntimeClass objects linked together in simple list
static CRuntimeClass* pFirstClass; // start of class list
CRuntimeClass* m_pNextClass; // linked list of registered classes
};
struct AFX_CLASSINIT
{ AFX_CLASSINIT(CRuntimeClass* pNewClass); };
#define RUNTIME_CLASS(class_name) (&class_name::class##class_name)
#define DECLARE_DYNAMIC(class_name) public: static CRuntimeClass class##class_name; virtual CRuntimeClass* GetRuntimeClass() const;
#define _IMPLEMENT_RUNTIMECLASS(class_name, base_class_name, wSchema, pfnNew) static char _lpsz##class_name[] = #class_name; CRuntimeClass class_name::class##class_name = { _lpsz##class_name, sizeof(class_name), wSchema, pfnNew, RUNTIME_CLASS(base_class_name), NULL }; static AFX_CLASSINIT _init_##class_name(&class_name::class##class_name); CRuntimeClass* class_name::GetRuntimeClass() const { return &class_name::class##class_name; }
#define IMPLEMENT_DYNAMIC(class_name, base_class_name) _IMPLEMENT_RUNTIMECLASS(class_name, base_class_name, 0xFFFF, NULL)
class CObject
{
public:
CObject::CObject() {
}
CObject::~CObject() {
}
virtual CRuntimeClass* GetRuntimeClass() const;
public:
static CRuntimeClass classCObject;
};
class CCmdTarget : public CObject
{
DECLARE_DYNAMIC(CCmdTarget)
public:
CCmdTarget::CCmdTarget() {
}
CCmdTarget::~CCmdTarget() {
}
};
class CWinThread : public CCmdTarget
{
DECLARE_DYNAMIC(CWinThread)
public:
CWinThread::CWinThread() {
}
CWinThread::~CWinThread() {
}
virtual BOOL InitInstance() {
return TRUE;
}
virtual int Run() {
return 1;
}
};
class CWnd;
class CWinApp : public CWinThread
{
DECLARE_DYNAMIC(CWinApp)
public:
CWinApp* m_pCurrentWinApp;
CWnd* m_pMainWnd;
public:
CWinApp::CWinApp() {
m_pCurrentWinApp = this;
}
CWinApp::~CWinApp() {
}
virtual BOOL InitApplication() {
return TRUE;
}
virtual BOOL InitInstance() {
return TRUE;
}
virtual int Run() {
return CWinThread::Run();
}
};
class CDocument : public CCmdTarget
{
DECLARE_DYNAMIC(CDocument)
public:
CDocument::CDocument() {
}
CDocument::~CDocument() {
}
};
class CWnd : public CCmdTarget
{
DECLARE_DYNAMIC(CWnd)
public:
CWnd::CWnd() {
}
CWnd::~CWnd() {
}
virtual BOOL Create();
BOOL CreateEx();
virtual BOOL PreCreateWindow();
};
class CFrameWnd : public CWnd
{
DECLARE_DYNAMIC(CFrameWnd)
public:
CFrameWnd::CFrameWnd() {
}
CFrameWnd::~CFrameWnd() {
}
BOOL Create();
virtual BOOL PreCreateWindow();
};
class CView : public CWnd
{
DECLARE_DYNAMIC(CView)
public:
CView::CView() {
}
CView::~CView() {
}
};
// global function
CWinApp* AfxGetApp();
//mfc.cpp
#include "my.h"
CMyWinApp theApp;
BOOL CMyWinApp::InitInstance()
{
m_pMainWnd = new CMyFrameWnd;
return TRUE;
}
CMyFrameWnd::CMyFrameWnd()
{
Create();
}
void PrintAllClasses() //输出“类别型录网“
{
CRuntimeClass* pClass;
//just walk through the simple list of registered classes
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";
}
}
void main()
{
CWinApp* pApp = AfxGetApp();
pApp->InitApplication();
pApp->InitInstance();
pApp->Run();
PrintAllClasses();
}
//my.h
#include <iostream.h>
#include "mfc.h"
class CMyWinApp:public CWinApp
{
public:
CMyWinApp::CMyWinApp(){}
CMyWinApp::~CMyWinApp(){}
virtual BOOL InitInstance();
};
class CMyFrameWnd:public CFrameWnd
{
public:
CMyFrameWnd();
~CMyFrameWnd(){}
};
class CMyDoc:public CDocument
{
public:
CMyDoc::CMyDoc(){}
CMyDoc::~CMyDoc(){}
};
class CMyView:public CView
{
public:
CMyView::CMyView(){}
CMyView::~CMyView(){}
};
//global function
void PrintAllClasses();
//my.cpp
#include "my.h"
CMyWinApp theApp;
BOOL CMyWinApp::InitInstance()
{
m_pMainWnd = new CMyFrameWnd;
return TRUE;
}
CMyFrameWnd::CMyFrameWnd()
{
Create();
}
void PrintAllClasses() //输出“类别型录网“
{
CRuntimeClass* pClass;
//just walk through the simple list of registered classes
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";
}
}
void main()
{
CWinApp* pApp = AfxGetApp();
pApp->InitApplication();
pApp->InitInstance();
pApp->Run();
PrintAllClasses();
}
时间： 2024-10-05 05:13:46