Yet another Error Handler question.

Sorry to post yet another Error Handling question, but it's doing my nut in.....

I have the following code:-


(if (= anyvariable nil) (*error*)) ; at various parts of the lisp

;error handler
(defun *error* (msg)
(princ "Error: No Objects Selected, Aborting")
(setvar "cmdecho" echo)
(setvar "osmode" osmd)
(princ)
);end defun

Which all seams to work, however when "Tools--->Check text in editor" on Vlisp I get the error :-
; warning: too few arguments: (*ERROR*) at the "IF"

What am I doing wrong?

Thanks for taking the time to look at the question, all help appreciated.

 

Look closely at your *Error* definition. Are there any arguments for the
function? Are you providing those arguments when you call the function?

--
R. Robert Bell


Sorry to post yet another Error Handling question, but it's doing my nut
in.....

I have the following code:-


(if (= anyvariable nil) (*error*)) ; at various parts of the lisp

;error handler
(defun *error* (msg)
(princ "Error: No Objects Selected, Aborting")
(setvar "cmdecho" echo)
(setvar "osmode" osmd)
(princ)
);end defun

Which all seams to work, however when "Tools--->Check text in editor" on
Vlisp I get the error :-
; warning: too few arguments: (*ERROR*) at the "IF"

What am I doing wrong?

Thanks for taking the time to look at the question, all help appreciated.

 

It should be (*error* <message>). The *error* function takes an argument,
which can be an empty string (*error* "") if you have no error message to
display. Some people are very adamant about programming an error handler
this way, however standard Acad error handler will also accept (*error* nil)
for no error message.

Unless you're going to repeat this same block of code, with slight
modifications, in every lisp program you write, IMHO it's bad practice to
hard-code the error message in the error handler like this. Remember that
any "error" including cancelling the routine will cause your error handler
to run, and your message will nearly always be spurious. You need to let
Acad fill in the message most of the time, except when you're explicitly
calling the function. This would be better:

(defun *error* (msg)
(princ msg)
<etc..>
)



If you want this to run when nothing is selected -- which would contradict
normal Acad conventions, since it normally keeps prompting you until you do
make a selection -- your calling routine should look something like this:

(defun c:widget (/ sset <etc.>)
(if (setq sset (ssget))
(run-widget-function)
(*error* "Nothing selected.")
)
(princ)
)

Using the mathmatical equality function "=" to compare somethingness to
nothingness is not really proper. If you want test for nil,
use (if (not <variable>) (<whatever>)). As in my example above, it's nearly
always possible -- and can be clearer -- to turn this around and use the
opposite test (if <variable> (<whatever>)) which eliminates one unecessary
operation.

 

Gent's

Sorted!!! Thanks for taking the time to help, and pointing me in the correct direction..

MG,