Copy attribute values from one block to others

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;;; ============================================================================
;;; CXATTCOPY - Copy attribute values from one block to others
;;; Version 1.0.0
;;; CADXChange LISP tools - https://cadxchange.net/resources/lisp/cxattcopy
;;; Tested in: AutoCAD (full version). Other programs that run AutoLISP may work but are not tested.
;;; Copyright (c) CADXChange. Free for personal and commercial use; do not resell or
;;; republish it as a collection. Terms: https://cadxchange.net/legal/lisp-terms
;;; ============================================================================

;; Copy attribute values from the block SOURCE to every block in TARGETS that has the same tags.
;; TAGS is a list of tag names, or nil for all tags of the source. Returns how many values were copied.
(defun cx:attcopy-run (source targets tags / n)
  (setq n 0)
  (foreach e targets
    (if (/= e source)
      (foreach tg (if tags tags (cx:tags (list source)))
        (if (and (cx:att-find e tg) (cx:att-find source tg))
          (progn
            (cx:att-set e tg (cx:att-get source tg))
            (setq n (1+ n)))))))
  n)

(defun c:CXATTCOPY ( / *error* cx:sv r source ss tags answer n)
  (setq *error* cx:err)
  (setq r (entsel "\nClick the block to copy the attribute values from: "))
  (cond
    ((null r))
    ((/= (cx:dxf 0 (entget (car r))) "INSERT") (princ "\nThat is not a block."))
    ((null (cx:attribs (car r))) (princ "\nThat block has no attributes."))
    (T
     (setq source (car r))
     (princ (strcat "\nAttributes: " (cx:join (cx:tags (list source)) ", ")))
     (if (setq ss (ssget '((0 . "INSERT") (66 . 1))))
       (progn
         (setq answer (cx:ask-str "Tags to copy, separated by commas (- for all)" "-"))
         (setq tags (if (member answer '("-" "")) nil (mapcar 'cx:trim (cx:split answer ","))))
         (cx:start '(("CMDECHO" . 0)))
         (setq n (cx:attcopy-run source (cx:ss->list ss) tags))
         (princ (strcat "\n" (itoa n) " value(s) copied."))
         (cx:end)))))
  (princ))


;;; ---- Shared helpers (used by the command above; identical in every CADXChange tool) ----

(defun cx:dxf (code ed)
  (cdr (assoc code ed)))

;; The ATTRIB entities of a block reference, in order.
(defun cx:attribs (ins / e out)
  (setq e (entnext ins))
  (while (and e (= (cx:dxf 0 (entget e)) "ATTRIB"))
    (setq out (cons e out) e (entnext e)))
  (reverse out))

;; The attribute tags found in a list of block references, each once, in order of appearance.
(defun cx:tags (names / out)
  (foreach e names
    (foreach a (cx:attribs e)
      (if (not (member (strcase (cx:dxf 2 (entget a))) (mapcar 'strcase out)))
        (setq out (append out (list (cx:dxf 2 (entget a))))))))
  out)

;; The ATTRIB of a block reference with the tag TAG (any case), or nil.
(defun cx:att-find (ins tag / r)
  (foreach a (cx:attribs ins)
    (if (and (not r) (= (strcase (cx:dxf 2 (entget a))) (strcase tag))) (setq r a)))
  r)

;; Replace the text of a TEXT, ATTRIB, ATTDEF or MTEXT.
(defun cx:text-set (ename str / ed out)
  (setq ed (entget ename))
  (if (= (cx:dxf 0 ed) "MTEXT")
    (progn
      ;; MTEXT stores text in 250-character pieces: 3 groups for the first pieces, 1 for the last
      (foreach p ed (if (not (member (car p) '(1 3))) (setq out (cons p out))))
      (setq out (reverse out))
      (while (> (strlen str) 250)
        (setq out (append out (list (cons 3 (substr str 1 250)))) str (substr str 251)))
      (setq ed (append out (list (cons 1 str)))))
    (setq ed (subst (cons 1 str) (assoc 1 ed) ed)))
  (entmod ed)
  (entupd ename)
  T)

;; Set the attribute TAG of a block reference to VALUE; returns T when the block has that attribute.
(defun cx:att-set (ins tag value / a)
  (if (setq a (cx:att-find ins tag))
    (progn (cx:text-set a value) (entupd ins) T)))

(defun cx:att-get (ins tag / a)
  (if (setq a (cx:att-find ins tag)) (cx:dxf 1 (entget a))))

;; Close the undo step and put the system variables back.
(defun cx:end ()
  (foreach v cx:sv (setvar (car v) (cdr v)))
  (command "_.UNDO" "_End")
  (setq cx:sv nil)
  (princ))

;; Error handler: restores everything, stays quiet on Esc.
(defun cx:err (msg)
  (if (> (getvar "CMDACTIVE") 0) (command))
  (cx:end)
  (if (and msg (not (wcmatch (strcase msg) "*BREAK*,*CANCEL*,*EXIT*")))
    (princ (strcat "\nError: " msg)))
  (princ))

(defun cx:join (lst delim / out)
  (setq out "")
  (foreach s lst
    (setq out (if (= out "") s (strcat out delim s))))
  (if lst out ""))

;; Ask for a string (spaces allowed) with a default; "-" means an empty string.
(defun cx:ask-str (msg def / v)
  (setq v (getstring T (strcat "\n" msg " <" def ">: ")))
  (cond ((= v "") def) ((= v "-") "") (T v)))

;; Remove spaces and tabs at both ends.
(defun cx:trim (s / a b)
  (setq a 1 b (strlen s))
  (while (and (<= a b) (member (substr s a 1) '(" " "\t"))) (setq a (1+ a)))
  (while (and (>= b a) (member (substr s b 1) '(" " "\t"))) (setq b (1- b)))
  (substr s a (max 0 (1+ (- b a)))))

;; Split STR at every DELIM (a one-character string) into a list of strings.
(defun cx:split (str delim / out cur i c)
  (setq out nil cur "" i 1)
  (while (<= i (strlen str))
    (setq c (substr str i 1))
    (if (= c delim)
      (setq out (cons cur out) cur "")
      (setq cur (strcat cur c)))
    (setq i (1+ i)))
  (reverse (cons cur out)))

;; Save the system variables in VARS ((name . value) ...), set them, and open one undo step.
;; The caller declares cx:sv as a local so the saved values live exactly as long as the command.
(defun cx:start (vars)
  (setq cx:sv (mapcar (function (lambda (v) (cons (car v) (getvar (car v))))) vars))
  (command "_.UNDO" "_Begin")
  (foreach v vars (setvar (car v) (cdr v)))
  (princ))

;; Selection set to a list of entity names.
(defun cx:ss->list (ss / i out)
  (setq i 0)
  (if ss
    (repeat (sslength ss)
      (setq out (cons (ssname ss i) out)
            i   (1+ i))))
  (reverse out))

(princ "\nCXATTCOPY loaded. Type CXATTCOPY to start.")
(princ)

More commands: Blocks and attributes

• CXATTFILLFill an attribute in many blocks
• CXATTNUMNumber a block attribute in sequence
• CXATTVISShow or hide block attributes
• CXBLKCOUNTCount blocks by name
• CXBLKREPLReplace blocks with another block
• CXBLKRENRename blocks in bulk
• CXBLKXPExplode blocks but keep their attribute text
• CXBLKSELSelect blocks by name or attribute value
• CXBLKATInsert a block at many places at once