Escaping from lisp...

I can't for the life of me get an escape to work in lisp.

Just as a test, I created a simple loop that counted to 10 and 'princ' ed the number. Thus I get 1-10 output to command line. I then put in a (COMMAND) break, so that if the counter hit 6, the routine should escape. Now when I run it, I get 12345*Cancel*678910.

This isn't the result I was expecting. How do I get a proper escape that will just quit out of a routine?

 

mr_nick

(exit)

or better:
<snip>
(setq counter 1)
(while (< counter 6)
(princ counter)
(setq counter (1+ counter))
)
<snip>

Cheers

 

You need *2* (command) statements.

the number. Thus I get 1-10 output to command line. I then put in a
(COMMAND) break, so that if the counter hit 6, the routine should escape.
Now when I run it, I get 12345*Cancel*678910.

will just quit out of a routine?

 

That wouldn't be my first choice.

I might arrange the logic so it can exit a loop
without trashing the entire lisp execution. Juerg
has demonstrated one way. Another way might be to
establish an exit or boundary condition like so:

(defun c:demo ( / i boundary done )

;; initialize vars

(setq
i 0
boundary 6
done nil
)

;; informative prompt

(princ
(strcat
"\nCounting 1 .. "
(itoa boundary)
" ..."
)
)

;; count 1 .. boundary, then exit the loop

(while (not done)
;; could use eq or =, though if
;; something incremented i an odd
;; amount an equality test might
;; fail to catch the breach of the
;; boundary condition event; the
;; <= will catch it regardless
(if (<= boundary (setq i (1+ i)))
(setq done t)
)
(print i)
)

;; show that we're still alive

(princ "\nStill alive, now exiting demo.")

;;; shhh

(princ)

)

Cheers.

You need *2* (command) statements.

the number. Thus I get 1-10 output to command line. I then put in a
(COMMAND) break, so that if the counter hit 6, the routine should escape.
Now when I run it, I get 12345*Cancel*678910.

will just quit out of a routine?

 

Another alternative to the actual loop portion might
be:

(while (not done)
(if (< boundary (setq i (1+ i)))
(setq done t)
(print i)
)
)

The important thing is there are a number of ways
of doing this; many of them give you the ability to
keep execution alive (funny words when together).

That wouldn't be my first choice.

I might arrange the logic so it can exit a loop
without trashing the entire lisp execution. Juerg
has demonstrated one way. Another way might be to
establish an exit or boundary condition like so:

(defun c:demo ( / i boundary done )

;; initialize vars

(setq
i 0
boundary 6
done nil
)

;; informative prompt

(princ
(strcat
"\nCounting 1 .. "
(itoa boundary)
" ..."
)
)

;; count 1 .. boundary, then exit the loop

(while (not done)
;; could use eq or =, though if
;; something incremented i an odd
;; amount an equality test might
;; fail to catch the breach of the
;; boundary condition event; the
;; <= will catch it regardless
(if (<= boundary (setq i (1+ i)))
(setq done t)
)
(print i)
)

;; show that we're still alive

(princ "\nStill alive, now exiting demo.")

;;; shhh

(princ)

)

Cheers.

You need *2* (command) statements.

<snip>

 

You can't use "(command) statements" to
break out of a LISP function.

 

The idea of my example was not to simply count to 6 as people seem to be
working to. This was a very simplistic approach to my problem. What I want
to do is carry out a full escape from my routine if a certain condition is
met. I have routines nested inside routines and if a condition is met in one
of these nested routines, I need to be able to escape completely - not just
out of the nested routine - just as you would if you hit the escape key. The
fact that I couldn't get the escape to happen on such a simple thing as the
count was just to prove to myself that it wasn't that simple. I have tried
the EXIT method, but for some reason, this keeps throwing up an 'error in
*error*'. Bit confusing since at this point I'm not using any kind of custom
error checking (

Is there a way of doing such a thing?

 

mr_nick

'exit' *is* a unfriendly break of code execution,
but normally you don't need it...
Another way to avoid 'exit' -> apply conditional
checks:
(cond
((not (ReadCfgFile))
((not (InitializeReactors))
((not (ImportLanguageProfiles))
(T (DoAllNecessaryScrapOnStartUp))
)

Cheers

 

Oops..

must be:
(defun MyStartInit ()
(cond
((not (ReadCfgFile)) (alert "Config error..."))
((not (InitializeReactors)) (alert "Reactor error..."))
((not (ImportLanguageProfiles)) (alert "Language error..."))
(T
(DoAllNecessaryScrapOnStartUp)
)
)
(princ)
)

Sorry