C / C++ / MFC

class CBusyState
{
public:

	// Constructor - by default the busy state is entered
	CBusyState(BOOL bEnterBusyState = TRUE, 
		SERVERCALL scBusyReply = SERVERCALL_RETRYLATER)
		: m_bBusy(FALSE)
	{
		// get the MFC message filter implementation. This will return NULL if called from a DLL.
		m_pMessageFilter = AfxOleGetMessageFilter();
		if (bEnterBusyState)
		   Begin(scBusyReply); // enter the busy state
	}

	// Destructor - ends the busy state (if previously entered)
	~COasisBusyState()
	{	
		End(); // end the busy state
	};

	// Begins the busy state. By default, any incoming COM calls will be
	// rejected, but retried later
	BOOL Begin(SERVERCALL scBusyReply = SERVERCALL_RETRYLATER)
	{	// check that we have a message filter, and that we're not already
		// busy.
		if (m_pMessageFilter && !m_bBusy)
		{	// set the reply code for IMessageFilter::HandlingIncomingCall()
			m_pMessageFilter->SetBusyReply(scBusyReply);
			// enter the busy state
			m_pMessageFilter->BeginBusyState();
			m_bBusy = TRUE;
		}
		return m_bBusy;
	}

	// Ends the busy state, if previously entered
	void End()
	{	// check that we have a message filter, and that we're busy
		if (m_pMessageFilter && m_bBusy)
		{	// end the busy state
			m_pMessageFilter->EndBusyState();
			m_bBusy = FALSE;
		}
	}

private:
	BOOL			m_bBusy;
	COleMessageFilter*	m_pMessageFilter;
};

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

"The pointy end goes in the other man." - Antonio Banderas (Zorro, 1998)

CMyView::CMyView() : CFormView(CMyView::IDD)
{
   //{{AFX_DATA_INIT(CMyView)
   //}}AFX_DATA_INIT

   CMyDoc* pDoc = GetDocument();
   if (pDoc) pDoc->RegisterClass(GetRuntimeClass()->m_lpszClassName, GetRuntimeClass());
}

CMyView::~CMyView()
{
   CMyDoc* pDoc = GetDocument();
   if (pDoc) pDoc->UnregisterClass(GetRuntimeClass()->m_lpszClassName);
}

BOOL CMyDoc::RegisterClass(const CString& strClassName, const CRuntimeClass* pClass)
{
	CRuntimeClass* pLookup = NULL;
	if (m_mapRuntimeClasses.Lookup(strClassName, (void*&)pLookup))
		UnregisterClass(strClassName); // Remove existing entry ???
	
	m_mapRuntimeClasses.SetAt(strClassName, ( void*& )pClass);
	return TRUE;
}

BOOL CMyDoc::UnregisterClass(const CString& strClassName)
{
	BOOL bRet = FALSE;

	CRuntimeClass* pLookup = NULL;
	if (m_mapRuntimeClasses.Lookup(strClassName, (void*&)pLookup))
		bRet = m_mapRuntimeClasses.RemoveKey(strClassName);

	return bRet;
} 

CFrameWnd* pFrame = (CFrameWnd*)AfxGetApp()->m_pMainWnd;
if (pFrame && pFrame->GetSafeHwnd())
{
    CMyDoc* pDoc = (CMyDoc*)pFrame->GetActiveDocument();
    if (pDoc) pDoc->Register(.....);
}