AutoCAD Visual LISP / AutoLISP :: Assign Variable Based On The Number Of Characters To Be Removed

(defun layun (target_obj / original_layer original_layer_info target_obj_atts new_layer )(setqoriginal_layer (cdr (assoc 8 (entget target_obj)))original_layer_info (tblsearch "layer" original_layer)target_obj_atts (entget target_obj));setq(if (or(wcmatch original_layer "*-P123"); REMOVES 4 CHARACTERS(wcmatch original_layer "*-P123456"); REMOVES 7 CHARACTERS(wcmatch original_layer "*-P123456789"); REMOVES 10 CHARACTERS );or(progn(setq new_layer (substr original_layer 1 (- (strlen original_layer) ??))) ; NEED TO ASSIGN VARIABLE TO MATCH THE NUMBER OF CHARACTERS TO REMOVE(if (not (tblsearch "layer" new_layer))(progn(entmake ;;;begin to make new layer(list'(0 . "LAYER")'(100 . "AcDbSymbolTableRecord")'(100 . "AcDbLayerTableRecord")(cons 2 new_layer) ;;; layer name(assoc 6 original_layer_info) ;;;re-use original linetype'(70 . 0) ;;;flags - use default flags(assoc 62 original_layer_info) ;;;re-use original color);list);entmake);progn);if(entmod (subst (cons 8 new_layer) (assoc 8 target_obj_atts) target_obj_atts)));progn);if);defun

assign a character where ? is shown so that it matches with the number of characters to remove based on the 3 lines above (see wcmatch lines).  At present, whatever number I replace that ?? with, it removes that number of characters from the layer that I selected (if it meets that WCMATCH criteria).  Another option which may be more difficult is to be able to have the routine look at the object layer and if it contains -N- or -D- or -NEW- or -DEMO- then to remove all the characters that follow these layer modifiers.  This way I can cleanly add another project modifier behind these modifers.