[SOLVED] Setter for a component

[pcurtis]

I have a component where I can assign another component as a property (see below). The problem is when I drop my component and say a button on a form, then assign the button to the source property, at first all is OK. If I then delete the button on the form the IDE crashes.
How can I fix that?

Code: Pascal  [Select][+][-]

1. unit MyZoomX;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, LResources, Forms, Controls, Graphics, Dialogs, ExtCtrls,
9.   StdCtrls, ComCtrls;
10.  
11. type
12.  
13.   { TMyZoomX }
14.  
15.   TMyZoomX = class(TComponent)
16.   private
17.     fSource : TControl;
18.     procedure SetSource(aValue : TControl);
19.     function  GetSource : TControl;
20.   protected
21.   public
22.     constructor Create(AOwner : TComponent); override;
23.   published
24.     property Source : TControl read GetSource write SetSource;
25.   end;
26.  
27. procedure Register;
28.  
29. implementation
30.  
31. constructor TMyZoomX.Create(AOwner : TComponent);
32. begin
33.   inherited Create(AOwner);
34. end;
35.  
36. procedure TMyZoomX.SetSource(aValue : TControl);
37. begin
38.   fSource := aValue;
39. end;
40.  
41. function TMyZoomX.GetSource : TControl;
42. begin
43.   Result := fSource;
44. end;
45.  
46. procedure Register;
47.  
48. begin
49.   RegisterComponents('Misc',[TMyZoomX]);
50. end;
51.  
52. end.
53.  

[pcurtis]

I originally tried

property Source : TControl read fSource write fSource;

[Sieben]

Same here with 2.0.10 - but isn't it a matter with TColorButton not overriding Notification...?

[wp]

now delete the Color Dialog and watch the crash..

This is because there is no Notification method in TColorButton. Add this to colorbutton.inc, and the crash will be gone (committed to Laz/main):

Code: Pascal  [Select][+][-]

1. procedure TColorButton.Notification(AComponent: TComponent; Operation: TOperation);
2. begin
3.   inherited;
4.   if (AComponent = FColorDialog) and (Operation = opRemove) then
5.     FColorDialog := nil;
6. end;

I doubt that it did work in Laz 2.0.6 because in 2.0.8 (I don't have 2.0.6 any more) the Notification method is missing, too.

[wp]

I already fixed it for TColorButton - see my previous post. Every control having other controls as properties must override the Notification method. The control to be deleted calls the Notification method and the owing control can set its reference to zero.

[pcurtis]

@wp - Thanks. Did the trick.

[wp]

jamie, please let's continue this discussion in the bugtracker.