object
is an abstract base class, from which all objects stored
in the graph must be derived. A synopsis of the ABC is:
class object: public Ptrlist { public: /* serialisation methods */ virtual void lpack(pack_t *buf)=0; virtual void lunpack(pack_t *buf)=0; /* virtual "constructors" */ virtual object* lnew() const=0; virtual object* lcopy() const=0; virtual ~object() {} virtual int type() const=0; /* return index into archetype table */ /* partition weightings - redefine in derived type if needed */ virtual idxtype weight() const {return 1;} virtual idxtype edgeweight(const objref& x) const {return 1;} };