Can the Interface part in an OLE class be overriden?

Scott Andrew -- sandrew@west.net
Tuesday, October 22, 1996

Environment:  VC 4.2b, Win95, NT 4.0     

I have a class defined like so:

class CFTPSitesShellView : public CCmdTarget
{
	DECLARE_DYNCREATE(CFTPSitesShellView)
	DECLARE_INTERFACE_MAP()


	CFTPSitesShellView();           // protected constructor used by dynamic
creation

// Attributes
public:
   CFTPSitesShellView(IShellFolder* pShellFolder);

// Operations
public:

// Overrides
	// ClassWizard generated virtual function overrides
	//{{AFX_VIRTUAL(CFTPSitesShellView)
	public:
	virtual void OnFinalRelease();
	//}}AFX_VIRTUAL

// Implementation
protected:

	virtual ~CFTPSitesShellView();

/*********************** IShellView interfaces ****************/
BEGIN_INTERFACE_PART(ShellView, IShellView)
        // *** IOleWindow methods ***
        STDMETHODIMP GetWindow(HWND * lphwnd);
        STDMETHODIMP ContextSensitiveHelp(BOOL fEnterMode);

        // *** IShellView methods ***
        STDMETHODIMP TranslateAccelerator(LPMSG lpmsg);
    #ifdef _FIX_ENABLEMODELESS_CONFLICT
        STDMETHODIMP EnableModelessSV(BOOL fEnable);
    #else
        STDMETHODIMP EnableModeless(BOOL fEnable);
    #endif
        STDMETHODIMP UIActivate(UINT uState);
        STDMETHODIMP Refresh();

        STDMETHODIMP CreateViewWindow(IShellView  *lpPrevView,
                                      LPCFOLDERSETTINGS lpfs, 
                                      IShellBrowser  * psb,
                                      RECT * prcView, 
                                      HWND  *phWnd);

        STDMETHODIMP DestroyViewWindow();
        
        STDMETHODIMP GetCurrentInfo(LPFOLDERSETTINGS lpfs);
        STDMETHODIMP AddPropertySheetPages(DWORD dwReserved,
                                        LPFNADDPROPSHEETPAGE lpfn,
                                        LPARAM lparam);

        STDMETHODIMP SaveViewState();
        STDMETHODIMP SelectItem(LPCITEMIDLIST pidlItem, UINT uFlags);
        
        STDMETHODIMP GetItemObject(UINT uItem, 
                                   REFIID riid,
                                   LPVOID *ppv);
       
END_INTERFACE_PART(ShellView)


	// Generated message map functions
	//{{AFX_MSG(CFTPSitesShellView)
		// NOTE - the ClassWizard will add and remove member functions here.
	//}}AFX_MSG

	DECLARE_MESSAGE_MAP()

  	IShellFolder* m_pShellFolder;                       // ShellFolder pointer
	ICommDlgBrowser* m_pCDB;                   // ICommdlgBrowser

	CShellViewWnd* m_pViewWnd   
	                                           //  listview in the right pane
	FOLDERSETTINGS m_FolderSettings;
	IShellBrowser* m_pShellBrowser;

   HWND m_hParentWnd;

   UINT m_uState;
};

The question I have. Is if I derive from my class. Can I override my
functions in the the IShellView interface part? If so how do I call back to
the default implementation? How do I declare the functions? 

Scott Andrew

---

Benny -- blee@filenet.com
Wednesday, October 23, 1996

[Mini-digest: 2 responses]


Nope, that is not possible.

One possible solution is:

class CFTPSitesShellView : public CCmdTarget {
 protected:
 virtual STDMETHODIMP GetWindow(HWND * lphwnd);
 {
  // base class implementation
 }

BEGIN_INTERFACE_PART(ShellView, IShellView)
        // *** IOleWindow methods ***
        STDMETHODIMP GetWindow(HWND * lphwnd)
   {
  METHOD_PROLOGUE(...)
  return pThis->GetWindow(lphwnd);
   }

      END_INTERFACE_PART(ShellView)
};


In your derived class, you have
class Derived : public CFTPSitesShellView {
 virtual STDMETHODIMP GetWindow(HWND * lphwnd);
 {
  // call base class
  CFTPSitesShellView::GetWindow(lphwnd);

  // .. do your extra stuff here
 }

};


This is the cleanest solution I have found so far.

Benny

 ----------
From:  Scott Andrew[SMTP:sandrew@west.net]
Sent:  Tuesday, October 22, 1996 10:14 AM
To:  mfc-l@netcom.com
Subject:  Can the Interface part in an OLE class be overriden?

Environment:  VC 4.2b, Win95, NT 4.0

I have a class defined like so:

class CFTPSitesShellView : public CCmdTarget
{
 DECLARE_DYNCREATE(CFTPSitesShellView)
 DECLARE_INTERFACE_MAP()


 CFTPSitesShellView();           // protected constructor used by dynamic
creation

// Attributes
public:
   CFTPSitesShellView(IShellFolder* pShellFolder);

// Operations
public:

// Overrides
 // ClassWizard generated virtual function overrides
 //{{AFX_VIRTUAL(CFTPSitesShellView)
 public:
 virtual void OnFinalRelease();
 //}}AFX_VIRTUAL

// Implementation
protected:

 virtual ~CFTPSitesShellView();

/*********************** IShellView interfaces ****************/
BEGIN_INTERFACE_PART(ShellView, IShellView)
        // *** IOleWindow methods ***
        STDMETHODIMP GetWindow(HWND * lphwnd);
        STDMETHODIMP ContextSensitiveHelp(BOOL fEnterMode);

        // *** IShellView methods ***
        STDMETHODIMP TranslateAccelerator(LPMSG lpmsg);
    #ifdef _FIX_ENABLEMODELESS_CONFLICT
        STDMETHODIMP EnableModelessSV(BOOL fEnable);
    #else
        STDMETHODIMP EnableModeless(BOOL fEnable);
    #endif
        STDMETHODIMP UIActivate(UINT uState);
        STDMETHODIMP Refresh();

        STDMETHODIMP CreateViewWindow(IShellView  *lpPrevView,
                                      LPCFOLDERSETTINGS lpfs,
                                      IShellBrowser  * psb,
                                      RECT * prcView,
                                      HWND  *phWnd);

        STDMETHODIMP DestroyViewWindow();
          

        STDMETHODIMP GetCurrentInfo(LPFOLDERSETTINGS lpfs);
        STDMETHODIMP AddPropertySheetPages(DWORD dwReserved,
                                        LPFNADDPROPSHEETPAGE lpfn,
                                        LPARAM lparam);

        STDMETHODIMP SaveViewState();
        STDMETHODIMP SelectItem(LPCITEMIDLIST pidlItem, UINT uFlags);
          

        STDMETHODIMP GetItemObject(UINT uItem,
                                   REFIID riid,
                                   LPVOID *ppv);
         

END_INTERFACE_PART(ShellView)


 // Generated message map functions
 //{{AFX_MSG(CFTPSitesShellView)
  // NOTE - the ClassWizard will add and remove member functions here.
 //}}AFX_MSG

 DECLARE_MESSAGE_MAP()

   IShellFolder* m_pShellFolder;                       // ShellFolder   
pointer
 ICommDlgBrowser* m_pCDB;                   // ICommdlgBrowser

 CShellViewWnd* m_pViewWnd
                                            //  listview in the right   
pane
 FOLDERSETTINGS m_FolderSettings;
 IShellBrowser* m_pShellBrowser;

   HWND m_hParentWnd;

   UINT m_uState;
};

The question I have. Is if I derive from my class. Can I override my
functions in the the IShellView interface part? If so how do I call back   
to
the default implementation? How do I declare the functions?

Scott Andrew

-----From: Ian Pepper 

As the functions you want available in the base class are not declared
virtual you will not be able to call them in a derived class.  Try
adding the virtual  keyword before each prototype and see if that works
as is.  Then you may be in with a chance of trying to deriev another
class.

Hope this is a starting point.

Ian

Ian Pepper, Flexicom Ltd.
ian@flexicom.ie

---

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