Problem in defining onClick in runtime with Pascal (Delphi / Lazarus)

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Problem in defining onClick in runtime with Pascal (Delphi / Lazarus)

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#1 by (2 votes)

1

I need to use procedure ClicaItem(Sender: TObject); in a OnClick created at run time by calling procedure CriaItem(nome:String); . However, in all my attempts, I could not assign item.OnClick to procedure ClicaItem . How do I proceed if an error occurs regarding incompatible types?

Error: Incompatible types: got address of procedure (TObject); Register "expected" procedure variable type of procedure (TObject) of object; Register > "

I want to clarify the procedure creation to the type accepted by OnClick, as well as how to do this assignment in the OnClick event.

NOTE: The item is normally created in runtime, but the line referring to OnClick is commented on due to the error before compiling.

delphi procedure runtime pascal lazarus

asked by anonymous 27.03.2016 / 08:03

1 answer

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score 2 · Accepted Answer

Your ClicaItem procedure must belong to an instance of a class (object);

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
     procedure ClicaItem(Sender: TObject);
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
   Button1.Click := ClicaItem;
end;

procedure TForm1.ClicaItem(Sender: TObject);
begin
   ShowMessage('ClicaItem');
end;

end.