MFC动态创建对象

#define IMPLEMENT_DYNCREATE(class_name, base_class_name) \
	CObject* PASCAL class_name::CreateObject() \
		{ return new class_name; } \
	IMPLEMENT_RUNTIMECLASS(class_name, base_class_name, 0xFFFF, \
		class_name::CreateObject)

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

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

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
};

//class_name::CreateObject --> pfnNew --> 创建对象的函数指针
//例子

IMPLEMENT_DYNCREATE(Cview1, CFormView)
=>
Object* PASCAL Cview1::CreateObject()
{ return new Cview1; } 

pWnd = (CWnd*)pViewClass->CreateObject();

///////////////////////////////////////////////
DECLARE_DYNCREATE(Cview1)

#define DECLARE_DYNCREATE(class_name) \
	DECLARE_DYNAMIC(class_name) \
	static CObject* PASCAL CreateObject();
#define DECLARE_DYNAMIC(class_name) \
protected: \
	static CRuntimeClass* PASCAL _GetBaseClass(); \
public: \
	static const AFX_DATA CRuntimeClass class##class_name; \
	virtual CRuntimeClass* GetRuntimeClass() const; \



CObject* CRuntimeClass::CreateObject()
{
	if (m_pfnCreateObject == NULL)
	{
		TRACE(_T("Error: Trying to create object which is not ")
			  _T("DECLARE_DYNCREATE \nor DECLARE_SERIAL: %hs.\n"),
			m_lpszClassName);
		return NULL;
	}

	CObject* pObject = NULL;
	TRY
	{
		pObject = (*m_pfnCreateObject)();
	}
	END_TRY

	return pObject;
}