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05.12.2008 at 06:45AM PDT, ID: 23394489
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Delphi 7 :: Component Development - Events without overriding

Asked by Marius0188 in Delphi Components, Delphi Programming, Delphi Programming Language

Hi Experts,

I am building a custom combobox component.
This component, by design, should execute internal code on the onchange event.
It is working 100% but the problem is when you assign a new onchange event in designtime or runtime
it does not execute the code in the component, which makes 100% sense but I need it to always execute
the onchange event in the design of the component.

What I basically did was create a procedure in in the Constructor of the component I assigned the onchange event to this procedure, see code snipped.

But like I mentioned, the developer / user can simply assign a new OnChange event which will just kick mine and that should NOT happen. Mine should always execute and if the developer / user has assigned a onchange then that one too.

Thanks.

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constructor TComboboxDateFilter.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  Parent := TWinControl(AOwner);
 
  Style := csDropDownList;
  Items.Add('Item 1');
  Items.Add('Item 2');
  ItemIndex := 0;
 
  OnChange := Change; //This is the assignment of the OnChange event
end;
[+][-]05.12.2008 at 06:58AM PDT, ID: 21547012

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[+][-]05.12.2008 at 07:02AM PDT, ID: 21547033

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Zones: Delphi Components, Delphi Programming, Delphi Programming Language
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Solution Provided By: ziolko
Participating Experts: 2
Solution Grade: A
 
 
[+][-]05.12.2008 at 07:03AM PDT, ID: 21547039

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[+][-]05.12.2008 at 07:07AM PDT, ID: 21547085

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[+][-]05.12.2008 at 07:10AM PDT, ID: 21547103

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[+][-]05.12.2008 at 07:12AM PDT, ID: 21547120

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[+][-]05.12.2008 at 07:28AM PDT, ID: 21547277

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