[newLISP] restart-router

The boss said I'd find Lisp addictive, and he was right.

The following is a newLISP implementation of a project attempted in VB6. The VB6 one failed to work consistently. The newLISP one hasn't failed yet.

The situation is that our ADSL connection goes down at random times, necessitating a walk down the hall to the comms room, wherein one turns off the power to the router so that it resets. I found out during the week that if I telnet into the router, give the appropriate password and the enter 'restart', that'll restart the router. Will it reduce the need to walk to the comms room? I really don't know as, all of a sudden, the router is working fine.

Here's the code:

(define (restart-router site , socket str telnetSite) (setq telnetSite (string site)) (setq socket (net-connect telnetSite 23)) (if socket (begin (net-receive socket str 512 "password:") (net-send socket "private\r\n") (net-receive socket str 512 "192.168.0.1>") (net-send socket "restart\r\n") (net-close socket) "Router restarted." ) "No connection. Could not restart router." ) ) (import "user32.dll" "MessageBoxA") (MessageBoxA 0 (restart-router "192.168.0.1") "restart-router" 0) (exit)

I really like the fourth parameter on the net-receive call; not only do I receive but I can look for something in what is received. I suppose testing for not receiving it would be good, but I'll leave that for another time.

Once the restart command is sent, there's no need to attempt a net-receive. Just close the connection. Note also the easy way of referring to and using a function in a DLL.

Using the link.lsp script (which comes in the standard newLISP install) I've been able to turn this code into a standalone EXE, and once I've established that it really does do the job, I'll install it on a couple of other machines in the office.

I suppose we actually need the exercise, but maybe we don't need the aggravation.

By the way, my last newLISP posting has generated an interesting conversation on comp.lang.misc (also mirrored on comp.lang.lisp).

© Copyright Bruce M. Axtens, 2009

[newLISP] reverse-find

I've always thought learning Lisp would be a good thing to do. The purists may argue that newLISP is not the best place to start. Oh well, too bad.

Below is my first (ever) lambda expression, a port of the VBScript RevInstr() function.

(set 'reverse-find (lambda (findThis inThis) (- (length inThis) (find (reverse findThis) (reverse inThis)) (length findThis))))

I must say I'm impressed with newLISP. Note that the minus (-) function above can receive more than one argument. A lot of the functions are like that.

Using the reverse-find is very like the (find) function, as below

(set 'toFind "dog") (set 'sentence "My first dog's fleas are on my second dog's blanket") (println (slice sentence (reverse-find toFind sentence) (length toFind))) ; "dog" (println (slice sentence (reverse-find toFind sentence))) ; "dog's blanket" (println (slice sentence (find toFind sentence))) ; "dog's fleas are on my second dog's blanket"

One thing that differentiates my lambda expression from the in-built find, is in the manner in which an error is flagged.

(catch (find "a" "b") 'result) (println result) ; nil (catch (reverse-find "a" "b") 'result) (println result) ; "ERR: value expected : (find (reverse findThis) (reverse inThis))\r\ncalled from user defined function reverse-find"

I'm not sure at this point why the difference and what to do about it. In my use of (find) I check for a result equal to nil, but with (reverse-find) I have to check to see if the result is a string. For example,

(catch (find "a" "b") 'result) (when (nil? result) (println "not found")) (catch (reverse-find "a" "b") 'result) (when (string? result) (println "not found"))

Doubtless, someone in the newLISP Fan Club will set me straight soon.

© Copyright Bruce M. Axtens, 2009