Attaching and Detaching Observers to a document, what is the correct way?

Hi,

I came across below code snippet in many of the sample PLugins where Observer is being:

• Attached on the kAfterOpenDocSignalResponderService
• Detached on the on kBeforeCloseDocSignalResponderService

Same DocRef is being used in both the cases but the Observer being referenced is new each time, so is it a correct way to do it? and Will it work?

GTTxtEdtResponder::attachDetachStoryObserver(UIDRef storyUIDRef, bool16 bAttach)
{  ErrorCode status = kFailure;  do{  // while we observe all stories (whether they are accessible or not), we only let accessible  // stories affect the cache. See the observer implementation for this logic.  InterfacePtr<IObserver> iGTTxtEdtObserver(storyUIDRef,IID_IGTTXTEDTSTORYOBSERVER);           //<--new reference created  if (iGTTxtEdtObserver == nil){  ASSERT_FAIL("GTTxtEdtResponder::attachDetachStoryObserver - no observer on story?");  break;  }  bAttach ? iGTTxtEdtObserver->AutoAttach() :iGTTxtEdtObserver->AutoDetach();  status = kSuccess;  }while (kFalse);  return status;
}

If you look closely, you can see that every time a detach is being called after attach, a new Observer reference is created.

Is correct way to do it?