[aspectl-devel] Errors in code from overview.html in aspectl-0.6

[Pascal Costanza]

Hi Jeff,

Thanks a lot for the bug report. Yes, I should have tested these things 
more carefully, but I have found the sources for these bugs. See the 
following responses.

On 10 Aug 2004, at 17:05, Jeff Caldwell wrote:

> (defpackage test-aspectl
>   (:use :aspectl :cl-user :cl))
> (in-package :test-aspectl)
>
> (define-join-point environment-pointcut
>     do-something)
> (define-join-point environment-pointcut
>     do-something-else)
> ; => (#<JOIN-PONT 216EEA1C> #<JOIN-PONT 2068D784>)
>
> (define-aspect-weaver environment-pointcut
> accept-environment-arg
>     (aspect-weaver join-point)
>   (declare (ignore aspect-weaver))
>   (create-method
>    (fdefinition (join-point-name join-point))
>    :qualifiers '(:around)
>    :lambda-list '(args &key (in-environment
>                                  *some-environment*)
>                        &allow-other-keys)
>    :specializers (list (find-class 't))
>    :declarations '((ignore args))
>    :body '(progn
>             (if (eq in-environment *some-environment*)
>                 (call-next-method)
>               (with-some-environment (in-environment)
>                 (call-next-method)))))))
> ; Error:
> ; The code from overview.html is missing
> ;  a parenthesis on the last line

Hm, it doesn't seem so. Maybe you have missed something during copy and 
paste?

> ;
> ; Error:
> ; => Undefined function DO-SOMETHING-ELSE in form
> ;    (SYMBOL-FUNCTION DO-SOMETHING-ELSE)

This cannot work. The example refers to the previous section where I 
have sketched methods do-something and do-something-else. Without those 
methods the code cannot work. Check out the sources of al-mixins.lisp 
for a more complete example. (I should provide a more illustrative 
example, this one is obviously too abstract.)

> (defclass person ()
>   ((name :accessor name :initarg :name)))
> ; => #<STANDARD-CLASS PERSON 217ABAD4>
>
> (with-class 'person
>   (class-add
>    :direct-slots
>    '(age :accessor age :initarg :age)))
> ; => #<STANDARD-CLASS PERSON 217ABAD4>
>
> (setq *p1* (make-instance 'person))
> ; => #<PERSON 20687C04>
>
> (inspect *p1*)
> ; =>
> ; #<PERSON 211E92A4> is a PERSON
> ; NAME      #<unbound slot>
> ;
> ; Error:
> ; The direct slot 'age' was not added to the class
> ;  'person

Yep. The bug is in al-mixins.lisp. See the aspect weaver WITH-CLASS 
ACCEPT-CLASS-ARG. There is a test (if (not (eq 'class *the-class*)) 
...). This should read (if (not (eq ,class *the-class*)) ...). (A comma 
instead of a quote.)

> (defmethod print-person-list :around (person-list)
>   (with-special-generic-function-scope (print-person*)
>     (defmethod* print-person* :before
>       ((scope dynamic) person)
>       (print "This person is part of a person list."))
>     (call-next-method)))
> ; => #<STANDARD-METHOD PRINT-PERSON-LIST (:AROUND)
>        (T) 2068C044>

My mistake. Instead of WITH-SPECIAL-GENERIC-FUNCTION-SCOPE this should 
read WITH-SPECIAL-FUNCTION-SCOPE. This is a leftover from 0.5.


Thanks a lot. I am going to update the website soon.


Pascal

--
Tyler: "How's that working out for you?"
Jack: "Great."
Tyler: "Keep it up, then."