Re: JESS: Get fact's slot value

First of all, you might tell us why you don't want to use modify? I 
can't see any good reason for that.

I think a perfectly valid notation in your case would be :
(modify ?new (expense (+ 2000 ?new.expense)))

Now if you're not familiar with LISP-like notation, you have a lot of 
guidance here:
http://www.jessrules.com/jess/docs/71/basics.html

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Gaëtan PRUVOST

LIMSI-CNRS BP 133
91403 Orsay Cedex France
Tel:+33 1 69858110

http://www.limsi.fr/Individu/pruvost/
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Le 22/11/2010 16:19, alvin0618 a écrit :
> expense = expense + 2000; // trying to get the previous amount add up with
> the current amount
>
> (deftemplate (slot name) (slot age) (slot expense))
> (bind ?new (assert (person (name Fred) (age 22) (expense 2000))))
>
> Instead of using the way like this:
> (modify ?new (expense 3000)) ;
>

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