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event for unnamed component

Posted on 2001-09-08
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Last Modified: 2011-09-20
Hi all.

I have a component which has property derived from TOwnedCollection.
Every item of collection is an object derived from TCollectionItem.
All items's property can be edited in designtime. All seems fine.

Now I have to add some event property to collection item. Nothing unusual.
I can see event name in object inspector, but can't assign it in designtime.

Error message:
"Can not create a default method name for unnamed component"

I added "Name" property to collection item and give names for all items, but it doesn't help.

Exploring VCL code I didn't found any object derived from TCollectionItem that has events.

I just want to be sure that it is not possible. Right? Can somebody guide me to the doc with explanations?

-----
Igor

PS:
I know that I can move property to main component level and use collection item as parameter to identify item which event occurs.
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Question by:ITugay
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2 Comments
 
LVL 10

Accepted Solution

by:
Jacco earned 1200 total points
ID: 6467236
I tried this in Delphi 5 and it works correctly also in design time. The error message you mention does not occur here. Maybe I haven't understood the problem well?

Regards Jacco

unit ButtonWithCollection;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TColl = class(TOwnedCollection)
  end;

  TCollItem = class(TCollectionItem)
  private
    FEvent: TNotifyEvent;
  published
    property Event: TNotifyEvent read FEvent write FEvent;
  end;

  TButtonWithCollection = class(TButton)
  private
    FColl: TColl;
  protected
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  published
    property Coll: TColl read FColl write FColl;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('SoSsA', [TButtonWithCollection]);
end;

{ TButtonWithCollection }

constructor TButtonWithCollection.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  FColl := TColl.Create(Self, TCollItem);
end;

destructor TButtonWithCollection.Destroy;
begin
  FColl.Free;
  inherited Destroy;
end;

end.
0
 
LVL 9

Author Comment

by:ITugay
ID: 6470185
Hi Jacco,

yes, you are right, it works. I found where is the problem in my code.

type
  TFieldDefinition = class(TCollectionItem)
  ...
  function GetNamePath: string; override;
end;
..........
function TFieldDefinition.GetNamePath: String;
begin
  Result := GetDisplayName;
end;

If I comment this method then all works as expected. But only name of item in object inspector's combobox become unusefull "CompName.PropName[nn]". OK, it's not a problem, I will do something with it.

You help me a lot. Thanx. Otherwise I still keep thinking that it's not possible. So points increased :-)


-----
Igor
0

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