[ns] how to pass an object to a classifier object

["Wayne W. Szeto" <wwszeto@hopper.math.uwaterloo.ca>]

I'm trying to pass an object gdr to the MPLSAddressClassifier object via
the bind function ( bind(const char*, TclObject**) ).  The object gdr is
of type GDR_type** (ie. GDR_type **gdr) and GDR_type is a subclass
of TclObject.  In the MPLSAddressClassifier constructor, I have tried
bind("gdr_", gdr) and bind ("gdr_", (TclObject**)gdr). (The 'gdr_' is a
field for MPLSAddressClassifier I defined in the tcl code by doing
"Classifier/Addr/MPLS set gdr_ 0").  The first one gives me a compliation
error and the second one gives me a segmentation fault.  What should be
the correct syntax?