(code) erasing layers and what not

[Mark Thomas]

;;;
;;; several function for erasing and purging entities on a given layer
;;;

(defun c:del-layer (/ ent l_name ss cntr amt ssent)

  ;;;
  ;;; erases all enities on selected layer then purges that layer
  ;;;

  (setvar 'clayer "0") ; set layer to 0

  (if
    ; make sure we get something
    (setq ent (car (entsel "\nSelect layer to remove: "))); test
    (progn
      ; extract the layer name from the entity
      (setq l_name (cdr (assoc 8 (entget ent))))

      ; create a selection set of all entites on layer 'l_name'
      (setq ss (ssget "X" (list (cons 8 l_name)))
            ; set 'cntr' to number of items in selection set
            cntr (1- (sslength ss))
            amt (itoa cntr); make a string from an integer
            )

      (if 
        ; does the sel set have anything in it
        (> cntr 0); test

        (while 
          ; as long as 'cntr' is greater than or equal to 0
          ; keep looping
          (>= cntr 0)

          ; extract the ename from the sel set
          (setq ssent (ssname ss cntr))
          (entdel ssent); delete that entity
          (setq cntr (1- cntr)); subtract 1 from cntr
          )

        )
      )
    )
  (command "_.purge" "LA" l_name "N")
  (princ (strcat "\nErased " amt " items"))
  (princ)
  )

;;;
;;; ===================================================================
;;;

(defun fx-rm-layer (l_name / ss sntr amt ssent)

  ;;;
  ;;; erase and purges all entites on 'l_name', a string
  ;;; returns the number of entites erased
  ;;;

  (setvar 'clayer "0")

  (if
    ; make sure the layer exists in the dwg
    (tblsearch "layer" l_name); test
    (progn ; continue
      (setq ss (ssget "X" (list (cons 8 l_name)))
            cntr (1- (sslength ss))
            amt cntr
            )

      (if (> cntr 0)
        (while
          (>= cntr 0)
          (setq ssent (ssname ss cntr))
          (entdel ssent)
          (setq cntr (1- cntr))
          )
        )
      )
    )
  (if (> amt 0)
    (command "_.purge" "LA" l_name "N")
    )
  ; return the amount of entites erased
  amt
  )

;;;
;;; ===================================================================
;;;

(defun fx-make-layer-list (/ ent l_name entlst)

  ;;;
  ;;; generate a list of layer names based on user selection
  ;;; and returns that list
  ;;;

  (while
    ; while user is selecting something continue loop
    (setq ent (car (entsel "\nSelect Item on Layer: "))); test

    ; extract layer name from selected entity
    (setq l_name (cdr (assoc 8 (entget ent))))
    (prompt l_name); output the layer

    (if 
      ; make sure the layer isn't already in the list
      (not (vl-position l_name entlst)); test

      ; if not then add it to the list
      (setq entlst (cons l_name entlst))
      )
    )
  )

;;;
;;; ===================================================================
;;;

(defun c:del-purge (/ lst)
  (setq cmd (getvar 'cmdecho))

  ; turn off the echo!
  (setvar 'cmdecho 0)

  (if
    ; make sure we get a list before we continue
    (setq lst (fx-make-layer-list)); test

    ; now that we have a list run 'fx-rm-layer' on each of those items
    (mapcar '(lambda (x) (fx-rm-layer x)) lst)
    )

  ; reset the variable
  (setvar 'cmdecho cmd)
  (princ)
  )

[CADTutor]

Thanks Mark for the generous contribution. Extremely useful - I'll add that to out AutoLISP archive if you don't mind.

[Mark Thomas]

Thanks Mark for the generous contribution. Extremely useful - I'll add that to out AutoLISP archive if you don't mind.

not at all.