DaniWeb Forum Index > Software Development > C++

C++ RSS

Calling a base class implementation in MFC

Please support our C++ advertiser: Intel Parallel Studio Home

•

Join Date: Oct 2008

Posts: 52

Reputation: Bhoot is an unknown quantity at this point

Solved Threads: 1

Bhoot

Offline

Junior Poster in Training

Calling a base class implementation in MFC

Nov 1st, 2008

Well, this post might seem weird but as i am very much confused, i thought to seek some help from here.
My question is : When should i call a base class implementation of a message handler in my own implementation? ( I am talking about MFC.)
For example :

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
 
afx_msg return_type MyFrameClass::OnMessageHandler ()
{
   CFrameWnd::OnMessageHandler();
   // my code
}
afx_msg return_type MyFrameClass::OnMessageHandler ()
{
   CFrameWnd::OnMessageHandler();
   // my code
}

I have also called the base class implementation of message handler in the above code.
However, as I found, it is necessary to call in some cases and it works if i dont do so in other cases.
How do I decide this? Or its just one more thing to remember?

Bhoot

•

Join Date: Aug 2005

Posts: 15,406

Reputation: Ancient Dragon has a reputation beyond repute

Solved Threads: 1467

Ancient Dragon Ancient Dragon is offline

Offline

Still Learning

Re: Calling a base class implementation in MFC

Nov 1st, 2008

I don't think there is any set rule -- depends on the message. Look at the message description in MSDN. Some say to return TRUE if you want to base class handler to be called, or FALSE if you don't. Also, in some cases you may want the base class to handle the message before you do, which is the case in the code snippet you posted. In other cases you may not want the base class to handle the message at all.

Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.

•

Join Date: Oct 2008

Posts: 52

Reputation: Bhoot is an unknown quantity at this point

Solved Threads: 1

Bhoot

Offline

Junior Poster in Training

Re: Calling a base class implementation in MFC

Nov 2nd, 2008

•

Originally Posted by Ancient Dragon

I don't think there is any set rule -- depends on the message. Look at the message description in MSDN. Some say to return TRUE if you want to base class handler to be called, or FALSE if you don't. Also, in some cases you may want the base class to handle the message before you do, which is the case in the code snippet you posted. In other cases you may not want the base class to handle the message at all.

You mean that its all the matter of remembering the handlers of which the base implementations are required to be called. And for the rest, its upon me whether to call or not. right?
OK then. I will try it out.