symysgames Posted November 29, 2016 Share Posted November 29, 2016 I often use selection sets in my programming but always encounter difficulties when they are empty. why is it so problematic? is it because of the nature of nil who is a atom and a list at the same time. Most of the time I make sure my selection set is never empty, I insert a dummy object and then remove once I don't need it, and I found it works ok . There are filters but I don't see how they can be of any use. For example if I have a selction set ss1 and then do (setq lg (sslength ss1)) if my selection set is empty it will not set lg to 0 but to nil. how can I overcome this without having to insert a dummy object. Quote Link to comment Share on other sites More sharing options...
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