I've a TButtonComboBox on a form for font selection and setup the OnChange event handler.

procedure TForm1.Form1Show(Sender: TObject);
begin
 cbFont.ItemIndex := 0;
 cbFont.OnChange := OnFontChange;
end;

procedure TForm1.OnFontChange(sender : TObject);
var v : variant;
begin
 v := cbFont.OnChange;   // (*)
 cbFont.OnChange := NIL; // disable handler

 // do something...

 cbFont.OnChange := v; // restore handler;
end;

On runtime the effect is a "to much recursion" or "not enough stack space". The reason is (*) is compiled to a function call.

// main_tform1.$p.tform1_onfontchange = function(sender)
// {
//    var $t = this, v;
//    v = $t.tform1_cbfont.tbindablecolumncontrol_fonchange();     <<--function call, should be a reference
//    $t.tform1_cbfont.tbindablecolumncontrol_fonchange = null;
//    $t.tform1_cbfont.tbindablecolumncontrol_fonchange = v;
// };

I'm now using type TNotifyEvent instead of variant and the JavaScript is correct. Example code in the attachment.

Michael Dreher

Michael,

<< On runtime the effect is a "to much recursion" or "not enough stack space". The reason is (*) is compiled to a function call. >>

Okay, I'll check it out.

Tim Young
Elevate Software
www.elevatesoft.com

Michael,

I'm putting together 2.06 B6 right now, and I'm going to have to hold off on implementing any fixes for this issue for now.  The primary reason is that there are limitations to what can be done with variants at the compiler level, especially with respect to method/function/procedure references.  There are situations where the compiler simply cannot figure out what to do with such types because there is insufficient information.  This isn't one of those cases, but the fact that there exist such cases gives me pause about recommending or allowing such constructs in the code, so I may simple turn them off and have the compiler issue a compilation error.

Tim Young
Elevate Software
www.elevatesoft.com