Disable Event

[Lainkes 0]

Hello,

I want to temporary disable an OnExit event on my TEdit component. And then enable it again.

How can I do that?

 

Many thanks

 

Lainkes

 

 

[dummzeuch 1664]

Assign NIL to it and later reassign the original event.

[Lainkes 0]

Maybe stupid question, but how do I reassign the original event?

 

Lainkes

 

 

[mvanrijnen 127]

var
 oldevent : TNotifyEvent;
begin
  oldevent := myComponent.OnExit;
  try
    myComponent.OnExit := nil; 
    
    ..... your code here ...

  finally
    myComponent.OnExit := oldevent ;
  end;
end; 

 

maybe expand the oldevent scope some more if you want to reassign in another method.

 

Edited August 24, 2022 by mvanrijnen

[Lainkes 0]

Thanks, this seems to work fine.

 

Lainkes

[Remy Lebeau 1633]

Another option is to leave the event handler assigned and use a separate variable instead, eg:

private
  IgnoreExit: Boolean;

...

procedure TMyForm.DoSomething;
begin
  IgnoreExit := True;
  try
    ...
  finally
    IgnoreExit := False;
  end;
end;

...

procedure TMyForm.Edit1Exit(Sender: TObject);
begin
  if IgnoreExit then Exit;
  ...
end;

I like using the component's Tag property for this task, if it is not being used for something else, eg:

procedure TMyForm.DoSomething;
begin
  Edit1.Tag := 1;
  try
    ...
  finally
    Edit1.Tag := 0;
  end;
end;

...

procedure TMyForm.Edit1Exit(Sender: TObject);
begin
  if Edit1.Tag <> 0 then Exit;
  ...
end;

 

Edited August 24, 2022 by Remy Lebeau