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From: chan@icsid2.comp (Pamela Chan)
Newsgroups: comp.windows.interviews
Subject: Callback Functions in 3.0b
Message-ID: <CHAN.91Jun23132258@icsid2.comp>
Date: 23 Jun 91 21:22:58 GMT
Sender: usenet@agate.berkeley.edu (USENET Administrator)
Distribution: comp
Organization: /n/icsid/db/u/chan/.organization
Lines: 61


I'm a beginner in InterViews and I'm currently working with 
InterViews 3.0b. 

This is probably a silly question but I do want to know 
the answer....

I'm trying to associate a callback funtion with a simple 
push button. I was looking at the sample program <alert.c> 
in the standard distribution. It works fine if I assigned 
World::quit as the callback function, but anything else will 
generate a compiler error:

/////////////////////////////////////////////////////////
class TestButton {
 public:
    TestButton(){};
    ~TestButton(){};
    void Press(){
	fprintf (stderr, "Test button pressed\n");	
    };
};

declare(ActionCallback, TestButton)
implement(ActionCallback, TestButton)

Glyph* MakeControlPanelDialog(Font* f, Color* fg, TestButton* tbutton) {

   Button* button1 = new Button(

//   *******error occurs here**********
     new ActionCallback(TestButton) (&tbutton, TestButton::Press),

//   replace the above line with the following and it works fine
//   new ActionCallback(World) (world, World::quit),

     new ChoiceItem(
	  new Bevel(new Margin(new Label("Test", f, fg), 3.0),
		 new Outset(color)),
          new Bevel(new Margin(new Label("Test", f, fg), 3.0),
		 new Inset(color))
     )
   );

========================================================
"main.c", line 31: error: bad argument list for 
TestButton_ActionCallback::TestButton_ActionCallback() 
(no match against any  TestButton_ActionCallback::TestButton_ActionCallback())
1 error

/////////////////////////////////////////////////////

I'm not sure what's declare() and implement() and
I'm only following the example blindly.
Can anyone explain to me what's wrong with my callback function?
Thanks.


------------------------------------------------------------------------
Pamela Chan			International Computer Science Institute
chan@icsi.berkeley.edu 		1947 Center Street, Berkeley, CA