[ROOT] TNode::SetParent()

From: Robert Hatcher (rhatcher@SLAC.stanford.edu)
Date: Wed Aug 29 2001 - 03:01:09 MEST 

Hi,
  Currently in TNode.h there is the declaration & definition for the
method to change a TNode's parent, e.g.:

   virtual void        SetParent(TNode *parent) {fParent=parent;}

But this does only half the work necessary.  The parent losing the
custody battle is never informed and continues to think they have
this child.  I think the right code is:

void TNode::SetParent(TNode *parent)
{
   // set the pointer to the parent, keep parents informed about who they have

   if (fParent)   fParent->GetListOfNodes()->Remove(this);
   else         gGeometry->GetListOfNodes()->Remove(this);

   fParent = parent;

   if (fParent) {
      fParent->BuildListOfNodes(); // new parent might not have list
      fParent->GetListOfNodes()->Add(this);
   }
   else gGeometry->GetListOfNodes()->Add(this);
}

Could this be the distributed definition?  There are times when
building a geometry it's easier to build a "containee" node before
one builds the "container" node and then after the fact make
the right adjustments.

Thanks,
-robert

Robert W. Hatcher   |  rhatcher@slac.stanford.edu
Research Associate  |  650.926.3171  [FAX 4001 or 3587]
Stanford University |  PO Box 4349, MS #63, Stanford CA 94309

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