1   
2   //this sample show how to deturmin if a object has an event assigned to it.
3   unit Unit1;
4   
5   interface
6   
7   uses
8     Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
9     Dialogs, StdCtrls;
10  
11  type
12    TForm1 = class(TForm)
13      Button1: TButton;
14      procedure Button1Click(Sender: TObject);
15    private
16      { Private declarations }
17    public
18      { Public declarations }
19    end;
20  
21  var
22    Form1: TForm1;
23  
24  implementation
25  
26  {$R *.dfm}
27  
28  procedure TForm1.Button1Click(Sender: TObject);
29  begin
30  
31    if addr(Button1.onclick)<>nil then//use addr to find addresss of onClick event
32     showmessage('This Button has a OnClick an event assigned to it')
33     else
34     showmessage('This Button do not have a OnClick an event assigned to it');
35  
36    if addr(Button1.onExit)<>nil then//use addr to find addresss of onExit event
37     showmessage('This Button has a OnExit an event assigned to it')
38     else
39     showmessage('This Button do not have a OnExit an event assigned to it')
40  
41  end;
42  
43  end.