Re: Question on Progress dialog

From:
"AliR \(VC++ MVP\)" <AliR@online.nospam>
Newsgroups:
microsoft.public.vc.mfc
Date:
Thu, 24 Jan 2008 18:35:31 GMT
Message-ID:
<TT4mj.389$5K1.384@newssvr12.news.prodigy.net>
"David Ching" <dc@remove-this.dcsoft.com> wrote in message
news:aL3mj.1189$uE.937@newssvr22.news.prodigy.net...

"AliR (VC++ MVP)" <AliR@online.nospam> wrote in message
news:ym3mj.5285$Rg1.960@nlpi068.nbdc.sbc.com...

A more elegant solution (IMHO) would be to use a base class for any class
that want's to use your progress control, which has a virtual function
(perhaps even pure virtual) that gets called when the user presses the
cancel key.

class CProgressBarReceiver
{
public:
   virtual void OnCancel() = NULL;
};

class CProgressDialog : public CDialog
{
   CProgressDialog(CProgressBarReceiver *pNotifyParent......);
   void SetNotifyParent(CProgressBarReceiver *pNotifyParent);
};

class CMyDocument : public CDocument, public CProgressBarReceiver
{
   virtual void OnCancel() { CloseDialog(); KillThread();
CloseDocument(); }
};


I suppose it's more elegant, but my personal preference because I value
terseness and ease of use is not to do it this way. Any caller can easily
create a static callback function, but forcing the caller to derive from
your class just to receive progress messages is a philosophy that leads to
massive class hierarchies that are not easily grok'd.

-- David


What about addressing the problem of having to have a static method. You
won't be able to distinguish between different instances of the class.
Sometime the easy way might not fulfill every need, that's what I was
pointing out.

AliR.

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