Selection Sets and Nongraphical Entities

Abstract

An outstanding advantage of using AutoLISP lies in our ability to manipulate selection sets. A selection set is a collection of entity names that we’ve grouped together for some purpose. A selection set is a new AutoLISP object type, the last one well encounter. It has the following printed representation: <Selection set: 1> Selection sets are actually very familiar to us; we create and use them all the time. When we select objects for a COPY or MOVE command, a selection set is built. The difference is that in AutoCAD we use a selection set once (or occasionally several times by invoking the Previous option), whereas in AutoLISP we give the selection set a name (via a symbol binding) and use it over and over again. Furthermore, our ability to easily access and alter the entity data makes selection sets more versatile than groups.