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Author Topic: Overview of "ACAD" Xdata scope?  (Read 2837 times)

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roy_043

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Overview of "ACAD" Xdata scope?
« on: February 20, 2014, 05:29:15 AM »
The "ACAD" Xdata appid is used for multiple purposes ("MVIEW", "DSTYLE" etc.?). Is there an overview somewhere? Can a single entity have "ACAD" Xdata for more than one purpose?

Example:
If I want to remove dim overrides can I just remove all "ACAD" Xdata or should I worry about data not related to the dimstyle?
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irneb

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Re: Overview of "ACAD" Xdata scope?
« Reply #1 on: February 22, 2014, 05:23:50 AM »
Quote from: roy_043 on February 20, 2014, 05:29:15 AM
If I want to remove dim overrides can I just remove all "ACAD" Xdata or should I worry about data not related to the dimstyle?
If you're worried that the dimension might have some other ACAD XData attached to it, then the dim overrides are placed within a DSTYLE subgroup of ACAD.

It starts with a (1000 . "DSTYLE") item and continues to the next (1002 . "}"). See CAB's example here: http://www.theswamp.org/index.php?topic=3313.msg40725#msg40725

Here's an example to clear only the DSTYLE portion from the ACAD XData group:
Code - Auto/Visual Lisp: [Select]
  1. (defun clear-xdata-dstyle  (entity / acad-xdata started)
  2.   (if (setq acad-xdata (assoc "ACAD" (cdr (assoc -3 (entget entity '("ACAD"))))))
  3.     (progn (setq acad-xdata
  4.                   (vl-remove-if
  5.                     '(lambda (item)
  6.                        (cond
  7.                          (started
  8.                           (or t (setq started (not (equal item '(1002 . "}"))))))
  9.                          ((equal item '(1000 . "DSTYLE")) (setq started t))))
  10.                     acad-xdata))
  11.            (entmod (list (cons -1 entity) (cons -3 (list acad-xdata)))))))
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Lee Mac

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Re: Overview of "ACAD" Xdata scope?
« Reply #2 on: February 22, 2014, 11:50:48 AM »
Quote from: irneb on February 22, 2014, 05:23:50 AM
Code - Auto/Visual Lisp: [Select]
  1. (or t (setq started (not (equal item '(1002 . "}"))))))

I don't think the second expression in this OR statement will ever be evaluated, since OR will cease evaluation when a given expression returns a non-nil value...

FWIW, I would write it as:
Code - Auto/Visual Lisp: [Select]
  1. (defun clear-dim-xd ( ent / lst tmp )
  2.     (if
  3.         (and
  4.             (setq lst (assoc "ACAD" (cdr (assoc -3 (entget ent '("ACAD"))))))
  5.             (setq tmp (member '(1000 . "DSTYLE") lst))
  6.         )
  7.         (entmod
  8.             (list (cons -1 ent)
  9.                 (cons -3
  10.                     (list
  11.                         (append
  12.                             (reverse (cdr (member '(1000 . "DSTYLE") (reverse lst))))
  13.                             (cdr (member '(1002 . "}") tmp))
  14.                         )
  15.                     )
  16.                 )
  17.             )
  18.         )
  19.     )
  20. )
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irneb

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Re: Overview of "ACAD" Xdata scope?
« Reply #3 on: February 22, 2014, 02:08:49 PM »
Quote from: Lee Mac on February 22, 2014, 11:50:48 AM
I don't think the second expression in this OR statement will ever be evaluated, since OR will cease evaluation when a given expression returns a non-nil value...
Ah! Sorry yes ... the t should be the last value evaluated on that line. Thanks for spotting it Lee.
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roy_043

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Re: Overview of "ACAD" Xdata scope?
« Reply #4 on: February 24, 2014, 05:05:25 AM »
Thank you for your answer irneb. You are right to point to the use of braces (group code 1002) inside "ACAD" Xdata. Even if currently an entity will only have one 'type' of "ACAD" Xdata attached, the braces suggest that this may change in the future.

Regarding the provided code samples:
Looking for the first occurrence of (1002 . "}") after (1000 . "DSTYLE") works for the current version of "DSTYLE" data. But Xdata braces can be nested. So checking for pairs would be safer.

I am still interested in an overview of "ACAD" Xdata though...
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CAB

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Re: Overview of "ACAD" Xdata scope?
« Reply #5 on: February 24, 2014, 07:53:30 AM »
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CAB

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Re: Overview of "ACAD" Xdata scope?
« Reply #6 on: February 24, 2014, 07:55:04 AM »
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Lee Mac

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Re: Overview of "ACAD" Xdata scope?
« Reply #7 on: February 24, 2014, 06:13:13 PM »
Quote from: roy_043 on February 24, 2014, 05:05:25 AM
But Xdata braces can be nested. So checking for pairs would be safer.

Good point Roy.
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roy_043

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Re: Overview of "ACAD" Xdata scope?
« Reply #8 on: February 25, 2014, 04:19:13 AM »
@ CAB: Thanks for the links. But I am not looking for general information on Xdata or dictionaries. My example is only there to illustrate why having an "ACAD" appid overview can be relevant.
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