Is it safe to use Free instead of Release for modal forms in Delphi?

Question

The Delphi online help says that Release should be used to remove a form from memory. However, in many examples for modal forms I have seen this construct:

MyForm := TMyForm.Create(nil);
try
  MyForm.ShowModal;
finally
  MyForm.Free;
end;

Is Free a safe way to destroy a modal form? As I can see in the source for ShowModal, Application.HandleMessage will be called until the ModalResult is not 0. Is this the reason why Free can not interfere with pending windows messages?

Answer 1

Absolutely, and you can also use the FreeAndNil routine. The FreeAndNil routine will only free the object if it is not already nil, and also set it to nil after the free. If you call free directly on an object which has already been freed, you get an Access Violation.

MyForm := TMyForm.Create(nil); 
try 
  MyForm.ShowModal; 
finally 
  FreeAndNil(MyForm); 
end;