Attribute that updates based on location

[EYNLLIB]

I'm attempting to make a block with an attribute/field that when placed inside a pre-defined set of 4 coordinates (rectangle), the attribute field will update with a custom message. Anyone have any guidance with this? I'm guessing it will need a diesel expression, which I'm not all that familiar with.

 

I'm hoping this is the right forum since it involves coding an expression

 

Thanks

[BIGAL]

So if understand correctly you want to place a field value which says "This is inside area1 " You can certainly do as a lisp updating a value but not as a field. Not sure if you can do a COND in a field expression say looking at a multiple XY points.

[EYNLLIB]

7 minutes ago, BIGAL said:

So if understand correctly you want to place a field value which says "This is inside area1 " You can certainly do as a lisp updating a value but not as a field. Not sure if you can do a COND in a field expression say looking at a multiple XY points.

 

Yeah, I can easily do a lisp but I don't want to have my engineers have to run a lisp every time for this workflow.

I'm trying to have detail numbers auto populate based on where the detail title is located. So if the detail title attribute is in a specific area of model space, it will always be 1/S3.0, etc

[BIGAL]

I probably can not help, but post a sample dwg so others can look at it.

[Danielm103]

Nothing I can think of that’s built in, so you would have to roll something.

 

With lisp, you would use an event to update the attributes, i.e. attached to regen

There’s more options with ARX, .NET or Python

- Create your own custom field

- Create an Overrule that updates the attributes on close

 

 

[mhupp]

On 10/10/2025 at 12:13 AM, EYNLLIB said:

 

Yeah, I can easily do a lisp but I don't want to have my engineers have to run a lisp every time for this workflow.

I'm trying to have detail numbers auto populate based on where the detail title is located. So if the detail title attribute is in a specific area of model space, it will always be 1/S3.0, etc

 

Have you looked into reactors to trigger the lisp? Never really used them didn't like the fact something is running without me knowing/realizing it.

 

 

-Edit

Would have to run this after ever copy or insert of a block to add a reactor to it. and i don't know how this affect the performance of the drawing. 

Edited 9 hours ago by mhupp

[EYNLLIB]

2 hours ago, mhupp said:

 

Have you looked into reactors to trigger the lisp? Never really used them didn't like the fact something is running without me knowing/realizing it.

 

(defun block-modified-callback (reactor obj)
  (let* (
    (ent (vlr-object-reactor-object reactor))
    (pos (cdr (assoc 10 (entget ent))))
  )
    ;; Define your target area (example: lower-left (0,0), upper-right (10,10))
    (if (and
          (>= (car pos) 0) (<= (car pos) 10)
          (>= (cadr pos) 0) (<= (cadr pos) 10)
        )
      (princ "\nBlock moved into target area!")     ;call lisp ?
      (princ "\nBlock moved outside target area.")  ;
    )
  )
)
(defun C:BlockReact ( / ss i ent obj)
  (setq ss (ssget "_X" '((0 . "INSERT")))) ;maybe limit to the blocks you want to update
  (if ss
    (progn
      (setq i 0)
      (while (< i (sslength ss))
        (setq ent (ssname ss i))
        (setq obj (vlr-object-reactor (vlax-ename->vla-object ent) nil '((:vlr-modified . block-modified-callback))))
        (setq i (1+ i))
      )
      (princ "\nReactors attached to block references.")
    )
    (princ "\nNo blocks found.")
  )
  (princ)
)

 

-Edit

Would have to run this after ever copy or insert of a block to add a reactor to it. and i don't know how this affect the performance of the drawing. 

 

I've never worked with reactors. I'll have to dig into it. Thanks!

[Lee Mac]

20 hours ago, mhupp said:

Have you looked into reactors to trigger the lisp? Never really used them didn't like the fact something is running without me knowing/realizing it.

 

(defun block-modified-callback (reactor obj)
  (let* (
    (ent (vlr-object-reactor-object reactor))
    (pos (cdr (assoc 10 (entget ent))))
  )
    ;; Define your target area (example: lower-left (0,0), upper-right (10,10))
    (if (and
          (>= (car pos) 0) (<= (car pos) 10)
          (>= (cadr pos) 0) (<= (cadr pos) 10)
        )
      (princ "\nBlock moved into target area!")     ;call lisp ?
      (princ "\nBlock moved outside target area.")  ;
    )
  )
)
(defun C:BlockReact ( / ss i ent obj)
  (setq ss (ssget "_X" '((0 . "INSERT")))) ;maybe limit to the blocks you want to update
  (if ss
    (progn
      (setq i 0)
      (while (< i (sslength ss))
        (setq ent (ssname ss i))
        (setq obj (vlr-object-reactor (vlax-ename->vla-object ent) nil '((:vlr-modified . block-modified-callback))))
        (setq i (1+ i))
      )
      (princ "\nReactors attached to block references.")
    )
    (princ "\nNo blocks found.")
  )
  (princ)
)

 

-Edit

Would have to run this after ever copy or insert of a block to add a reactor to it. and i don't know how this affect the performance of the drawing. 

 

Don't create a new reactor for every object - this is likely to severely impact performance - only one object reactor is required with a set of owning objects. Aside, you're missing the definition for your (let*) function.

[BIGAL]

If you use a reactor it is a lisp anyway and has to be ran every time you add the block, so as I suggested much easier to do a lisp that looks at the XY point and updates, a lisp will run through multiple blocks very fast and update all. Just make the lisp insert the block 1st.

[Steven P]

Reading this one, what is the objection to the engineers running a LISP? You could add it as a button, in the ribbon, or as a command to suit their preferences, and if you make it easier for them they'll use it.

 

For example a single command to draw the rectangle and insert the block instead of 3 or 4 commands makes things quicker and easier, the engineers should jump on that (every speed improvement is after all another few seconds to go and make another coffee!)