|  | Home | Libraries | People | FAQ | More | 
            Return an object pointer if this is an
            object, else return nullptr
          
object* if_object();
            If this->kind() == kind::object,
            returns a pointer to the underlying object. Otherwise, returns nullptr.
          
The return value is used in both a boolean context and to assign a variable:
if( auto p = jv.if_object() ) return *p;
Constant.
No-throw guarantee.