What's if the user pressed CANCEL while running a lisp

[David Bethel]

Here is what I would consider a minimum for a robust error trap:

 

[color=#8b4513];++++++++++++ Set Modes & Error ++++++++++++++++++++++++++++++++++[/color]
[b][color=BLACK]([/color][/b]defun err_smd [b][color=FUCHSIA]([/color][/b][b][color=FUCHSIA])[/color][/b]

[color=#8b4513];;;START AN UNDO GROUP[/color]
[b][color=FUCHSIA]([/color][/b]and [b][color=NAVY]([/color][/b]zerop [b][color=MAROON]([/color][/b]getvar [color=#2f4f4f]"UNDOCTL"[/color][b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b]
     [b][color=NAVY]([/color][/b]command [color=#2f4f4f]"_.UNDO"[/color] [color=#2f4f4f]"_ALL"[/color][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]
[b][color=FUCHSIA]([/color][/b]and [b][color=NAVY]([/color][/b]= [b][color=MAROON]([/color][/b]logand [b][color=GREEN]([/color][/b]getvar [color=#2f4f4f]"UNDOCTL"[/color][b][color=GREEN])[/color][/b] 2[b][color=MAROON])[/color][/b] 2[b][color=NAVY])[/color][/b]
     [b][color=NAVY]([/color][/b]command [color=#2f4f4f]"_.UNDO"[/color] [color=#2f4f4f]"_CONTROL"[/color] [color=#2f4f4f]"_ALL"[/color][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]
[b][color=FUCHSIA]([/color][/b]and [b][color=NAVY]([/color][/b]= [b][color=MAROON]([/color][/b]logand [b][color=GREEN]([/color][/b]getvar [color=#2f4f4f]"UNDOCTL"[/color][b][color=GREEN])[/color][/b] 8[b][color=MAROON])[/color][/b] 8[b][color=NAVY])[/color][/b]
     [b][color=NAVY]([/color][/b]command [color=#2f4f4f]"_.UNDO"[/color] [color=#2f4f4f]"_END"[/color][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]
[b][color=FUCHSIA]([/color][/b]command [color=#2f4f4f]"_.UNDO"[/color] [color=#2f4f4f]"_GROUP"[/color][b][color=FUCHSIA])[/color][/b]

[color=#8b4513];;:DEFINE ERROR TRAP[/color]
[b][color=FUCHSIA]([/color][/b]setq *error* [b][color=NAVY]([/color][/b]lambda [b][color=MAROON]([/color][/b]msg[b][color=MAROON])[/color][/b]
               [b][color=MAROON]([/color][/b]while [b][color=GREEN]([/color][/b]> [b][color=BLUE]([/color][/b]getvar [color=#2f4f4f]"CMDACTIVE"[/color][b][color=BLUE])[/color][/b] 0[b][color=GREEN])[/color][/b]
                      [b][color=GREEN]([/color][/b]command[b][color=GREEN])[/color][/b][b][color=MAROON])[/color][/b]
               [b][color=MAROON]([/color][/b]and [b][color=GREEN]([/color][/b]/= msg [color=#2f4f4f]"quit / exit abort"[/color][b][color=GREEN])[/color][/b]
                    [b][color=GREEN]([/color][/b]princ [b][color=BLUE]([/color][/b]strcat [color=#2f4f4f]"\nError: *** "[/color] msg [color=#2f4f4f]" *** "[/color][b][color=BLUE])[/color][/b][b][color=GREEN])[/color][/b][b][color=MAROON])[/color][/b]
               [b][color=MAROON]([/color][/b]and [b][color=GREEN]([/color][/b]= [b][color=BLUE]([/color][/b]logand [b][color=RED]([/color][/b]getvar [color=#2f4f4f]"UNDOCTL"[/color][b][color=RED])[/color][/b] 8[b][color=BLUE])[/color][/b] 8[b][color=GREEN])[/color][/b]
                    [b][color=GREEN]([/color][/b]command [color=#2f4f4f]"_.UNDO"[/color] [color=#2f4f4f]"_END"[/color] [color=#2f4f4f]"_.U"[/color][b][color=GREEN])[/color][/b][b][color=MAROON])[/color][/b]
               [b][color=MAROON]([/color][/b]err_rmd[b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b]

[color=#8b4513];;;DECLARE SYSVAR ATOMS[/color]
      err_var '[b][color=NAVY]([/color][/b][b][color=MAROON]([/color][/b][color=#2f4f4f]"CMDECHO"[/color]   . 0[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b][color=#2f4f4f]"OSMODE"[/color]    . 0[b][color=MAROON])[/color][/b]
                [b][color=MAROON]([/color][/b][color=#2f4f4f]"SNAPMODE"[/color]  . 1[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b][color=#2f4f4f]"ORTHOMODE"[/color] . 1[b][color=MAROON])[/color][/b]
                [b][color=MAROON]([/color][/b][color=#2f4f4f]"ELEVATION"[/color] . 0[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b][color=#2f4f4f]"THICKNESS"[/color] . 0[b][color=MAROON])[/color][/b]
                [b][color=MAROON]([/color][/b][color=#2f4f4f]"UCSICON"[/color]   . 1[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b][color=#2f4f4f]"HIGHLIGHT"[/color] . 1[b][color=MAROON])[/color][/b]
                [b][color=MAROON]([/color][/b][color=#2f4f4f]"COORDS"[/color]    . 2[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b][color=#2f4f4f]"DRAGMODE"[/color]  . 2[b][color=MAROON])[/color][/b]
                [b][color=MAROON]([/color][/b][color=#2f4f4f]"DIMZIN"[/color]    . 1[b][color=MAROON])[/color][/b]
                [b][color=MAROON]([/color][/b][color=#2f4f4f]"CECOLOR"[/color]   . [color=#2f4f4f]"BYLAYER"[/color][b][color=MAROON])[/color][/b]
                [b][color=MAROON]([/color][/b][color=#2f4f4f]"CELTYPE"[/color]   . [color=#2f4f4f]"BYLAYER"[/color][b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]

[color=#8b4513];;;SET SYSVAR ATOMS[/color]
[b][color=FUCHSIA]([/color][/b]foreach v err_var
  [b][color=NAVY]([/color][/b]and [b][color=MAROON]([/color][/b]getvar [b][color=GREEN]([/color][/b]car v[b][color=GREEN])[/color][/b][b][color=MAROON])[/color][/b]
       [b][color=MAROON]([/color][/b]setq err_rst [b][color=GREEN]([/color][/b]cons [b][color=BLUE]([/color][/b]cons [b][color=RED]([/color][/b]car v[b][color=RED])[/color][/b] [b][color=RED]([/color][/b]getvar [b][color=PURPLE]([/color][/b]car v[b][color=PURPLE])[/color][/b][b][color=RED])[/color][/b][b][color=BLUE])[/color][/b] err_rst[b][color=GREEN])[/color][/b][b][color=MAROON])[/color][/b]
       [b][color=MAROON]([/color][/b]setvar [b][color=GREEN]([/color][/b]car v[b][color=GREEN])[/color][/b] [b][color=GREEN]([/color][/b]cdr v[b][color=GREEN])[/color][/b][b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]

[b][color=FUCHSIA]([/color][/b]princ[b][color=FUCHSIA])[/color][/b][b][color=BLACK])[/color][/b]

[color=#8b4513];++++++++++++ Return Modes & Error +++++++++++++++++++++++++++++++[/color]
[b][color=BLACK]([/color][/b]defun err_rmd [b][color=FUCHSIA]([/color][/b][b][color=FUCHSIA])[/color][/b]

[color=#8b4513];;;RESET SYSVAR ATOMS[/color]
 [b][color=FUCHSIA]([/color][/b]foreach v err_rst [b][color=NAVY]([/color][/b]setvar [b][color=MAROON]([/color][/b]car v[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b]cdr v[b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]

[color=#8b4513];;;END THE UNDO GROUP[/color]
 [b][color=FUCHSIA]([/color][/b]command [color=#2f4f4f]"_.UNDO"[/color] [color=#2f4f4f]"_END"[/color][b][color=FUCHSIA])[/color][/b]

[color=#8b4513];;;EXIT CLEAN[/color]
 [b][color=FUCHSIA]([/color][/b]prin1[b][color=FUCHSIA])[/color][/b][b][color=BLACK])[/color][/b]

[color=#8b4513];************ Main Program ***************************************[/color]
[b][color=BLACK]([/color][/b]defun c:test [b][color=FUCHSIA]([/color][/b]/ *error* err_var err_rst[b][color=FUCHSIA])[/color][/b]
 [b][color=FUCHSIA]([/color][/b]err_smd[b][color=FUCHSIA])[/color][/b]

 [color=#8b4513];;;PLACE YOUR CODE HERE[/color]

 [b][color=FUCHSIA]([/color][/b]err_rmd[b][color=FUCHSIA])[/color][/b][b][color=BLACK])[/color][/b]

 

This will cancel any command that is active at the time of the error/escape, reset the sysvars modes and undo any changes to the database that the the program has made.

 

IMO, Just redefining *error* so that it doesn't display an error is misleading the user into thinking that everything has been reset is not a good thing. My $0.02 -David

Edited October 20, 2010 by David Bethel

[alanjt]

I guess now it's correct .

 

(defun *error* (msg)
   (if (and msg (not (wcmatch (strcase msg) "*BREAK*,*CANCEL*,*QUIT*,")))
     (progn
       (princ (strcat "\nError: " msg))
(and os (setvar 'osmode os))
     )
   )
)

 

Tell me please .

 

Many thanks

Dude, I posted you the correct way: http://www.cadtutor.net/forum/showthread.php?53521-What-s-if-the-user-pressed-CANCEL-while-running-a-lisp&p=362805&viewfull=1#post362805

 

You want the reset to occur, regardless of the error message. The message portion of the code should not be touched.