Question

I have a form dynamically created that needs to be destroyed:

• later (at application shutdown) IF AssignData succeeds, or
• immediately in case AssignData crashes.

Since the form is owned by the application, it is not safe to just call FreeAndNil on it. But Close also won’t work; it won’t close the window.

FrmLoader:= TFrmLoader.Create(Application);  <----- Application is the Owner                            
TRY
  FrmLoader.AssignData(FileData);                                      
EXCEPT                                                              
  FreeAndNil(FrmLoader);  // <------ unsafe                                            
  FrmLoader.Close;        // <------ this is the safe method to close it but won't work
  RAISE;       
END;
FrmLoader.DoStuff;

Answer 1

It is perfectly safe to call Free on a form that is owned. Or pass the form to FreeAndNil. And that is the right way to dispose of your form.

So, this code does what you need.

FrmLoader:= TFrmLoader.Create(Application);
TRY
  FrmLoader.AssignData(FileData);                                      
EXCEPT                                                              
  FreeAndNil(FrmLoader);
  RAISE;       
END;