Yes, a function can have only one advice. This wasn't originally the
case, but experience showed that allowing multiple advice per function
caused problems -- it was too easy to create infinite loops, for
example.
You can solve your problem with a before-advice which unbinds the
variables, calls bsave explicitly, rebinds the variables, and then
returns. If you check the documentation, it explains that explicitly
returning from a before-advice will result in the adviced function not
being called automatically.
On Oct 7, 2010, at 8:44 AM, Gaëtan Pruvost wrote:
Hi everybody,
I have a problem with defadvice's behavior. It looks like you can't
add both a "before" and an "after" advice to the same function.
Here is an example that demonstrates it
(deffunction f ()
(printout t "during f" crlf))
(defadvice before f (printout t "before f" crlf))
(defadvice after f (printout t "after f" crlf))
(f)
It prints:
Jess> (batch "test.clp")
during f
after f
Jess>
Looks like the after overwrote the before one and there is no way to
define both at the same time...
I'm new to Jess so I hope this question is not stupid but i looked
in documentation and in the old mailling-list messages and found no
explaination for it. Is it the intended behaviour (in which case it
would be good to precise it in the doc) or a bug? I'm using the last
Jess71p2.
I needed this to unbind global variables before a bsave and rebind
after the bsave (this variable refers to a java Logger which is not
serializable). I've found another solution wihtout using defadvice
but I find the defadvice more elegant.
Best regards
--
***********************************
Gaëtan PRUVOST
LIMSI-CNRS BP 133
91403 Orsay Cedex France
Tel:+33 1 69858110
http://www.limsi.fr/Individu/pruvost/
***********************************
<gaetan_pruvost.vcf>
---------------------------------------------------------
Ernest Friedman-Hill
Informatics & Decision Sciences, Sandia National Laboratories
PO Box 969, MS 9012, Livermore, CA 94550
http://www.jessrules.com
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