LISP for automatic layer changing

[liamQ8LGU]

AutoCAD Experts,

I am trying to implement a LISP routine where the layers from an external consultants DWG file are automatically changed to reflect my layer conventions. I've found an easy LISP routine (attached) which uses the laymrg function, however the issue is when the layer does not exist in the DWG (which is common as consultants often purge their DWG's before releasing) the LISP will not function properly. Any advice on how to overcome this issue? Any help would be greatly appreciated.

[Sea-Haven]

To stop layer is missing problems just add does layer exist 1st, (tblsearch "LAYER" layername) will return T if layer exists. 

[liamQ8LGU]

Thank you, I think this is the solution but I am a LISP routine noob and not sure exactly how to implement. Are you able to attach the original LISP I included with the tblsearch as required?

[Sea-Haven]

Need a rewrite 

(setq laylst (list (list "RIDGER" "Ex_Building Roof")
(list "DTM_Existing_contours" "Ex_Contours")
(list "PAVER" "Ex_Pavers")
(list "RIDGE" "Ex_Building Roof")))

(foreach lay laylst
(if (tblsearch "layer" (cadr lay))
(Command "_laymrg" "t" (car lay) "" "t" (cadr lay) "y")
)
)

Not tested. 

[liamQ8LGU]

Unfortunately I'm not having any luck with merging the two LISP's. I'm still getting the same problem when a layer doesn't exist.

[ВeekeeCZ · Accepted solution]

Maybe use a feature that is already built in? SEE HERE 

[Kent1Cooper]

Shouldn't it test for the presence of both Layers for each merge?  How about [untested]:

(defun C:LC (/ pairs)
  (setq pairs
    '(
      ("RIDGER" "Ex_Building Roof")
      ("DTM_Existing_contours" "Ex_Contours")
      ("PAVER" "Ex_Pavers")
      ("RIDGE" "Ex_Building Roof")
    ); list
  ); setq
  (foreach pair pairs
    (if (and (tblsearch "layer" (car pair)) (tblsearch "layer" (cadr pair)))
    (command "_.laymrg" "_t" (car pair) "" "_t" (cadr pair) "y")
  ); foreach
  (prin1)
); defun

[liamQ8LGU]

Perfect! Thanks so much. Any idea if there is a similar option for blocks??

[Sea-Haven]

Pretty obvious

(tblsearch "BLOCK" "Northn")
((0 . "BLOCK") (2 . "NORTHN") (70 . 0) (10 0.0 0.0 0.0) (-2 . <Entity name: 3d3ef360>))