How to catch unhandled exception that are raised in background thread?

Question

I have for habit to execute anonymous thread like :

TThread.CreateAnonymousThread(
   procedure
   begin
     .....
   end).start;

But the problem is that if some unhandled exception will raise during the execution, then i will be not warned about it! For the main thread we have Application.OnException. Do we have something similar for background thread ?

Answer 1

TThread has a public FatalException property:

If the Execute method raises an exception that is not caught and handled within that method, the thread terminates and sets FatalException to the exception object for that exception. Applications can check FatalException from an OnTerminate event handler to determine whether the thread terminated due to an exception.

For example:

procedure TMyForm.DoSomething;
begin
  ...
  thread := TThread.CreateAnonymousThread(...);
  thread.OnTerminate := ThreadTerminated;
  thread.Start;
  ...
end;

procedure TMyForm.ThreadTerminated(Sender: TObject);
begin
  if TThread(Sender).FatalException <> nil then
  begin
   ...
  end;
end;