Re: JESS: Strange behaviour of defadvice

  Thanks for the quick reply.

Your solution is perfect. I had seen in the doc that you could use 
"return" to prevent the adviced function to be called but I didn't think 
of it as a solution to my problem... That works great, though I was kind 
of expecting an infinite loop but it seems smart enough not to call the 
advice again.

Thanks for the help.
BTW, I'm working on a binding Jess<->OWL that would rely on Jena if 
people are interested...
I know there exists a bridge for OWL/SWRL in Protege but I was not very 
happy with it and also Jena is much lighter than Protege.



Le 07/10/2010 17:03, Ernest Friedman-Hill a écrit :
> 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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