ESC use with lisp

[LSElite]

Hey all

Is there an wasy way of writing your lisps so that if the user presses the escape key during its execution that it exits the program in a desired way? eg restoring settings such as filedia and tilemode before exiting.

Cheers

[Tom Beauford]

Post by the offical *error* routine guru:
http://forums.augi.com/showthread.ph...122#post996122
Man has taught classes on the subject here on AUGI.

[peter]

Hey all

Is there an wasy way of writing your lisps so that if the user presses the escape key during its execution that it exits the program in a desired way? eg restoring settings such as filedia and tilemode before exiting.

Cheers

Here is an example of what I think you want...

(defun C:TestEscape (/ *error* intCmdEcho strMessage)
 (setq intCmdEcho (getvar "cmdecho"))
 (setvar "cmdecho" 0)
 (defun *error* (strMessage)
  (setvar "cmdecho" intCmdEcho)
  (princ strMessage)
  (princ)
 )
 (print "Do Something: ")
 (setvar "cmdecho" intCmdEcho)
 (princ)
)

[BlackBox]

I prefer to nest the *error* function within the main code, defining the function as a local variable... I also choose to define the localized *error* handler immediately (prior to any system variable changes are made, etc.). While unlikely if not prompting the user for input, it is possible for one to immediately hit escape after a system variable has been changed, and before the *error* handler has been defined, which would result in a system variable value not being restored.

Example:

(defun c:FOO ( / *error* oldCmdecho foo)

  (defun *error* (msg)
    (if oldCmdecho
      (setvar 'cmdecho oldCmdecho)
    )
    (cond ((not msg))                                                   ; Normal exit
          ((member msg '("Function cancelled" "quit / exit abort")))    ; <esc> or (quit)
          ((princ (strcat "\n** Error: " msg " ** ")))
    )                                                                   ; Fatal error, display it
    (princ)
  )

  (if (and (setq oldCmdecho (getvar 'cmdecho))
           (setq foo (getstring "\nHit <ESC>))
      )
    (prompt "\n** You didn't hit <ESC> like I asked you to ** ")
  )
  (*error* nil)
)

[irneb]

Another thread discussing the use of nested and global error handlers at length: http://forums.augi.com/showthread.ph...Error-Handling