Re: JESS: Odd accumulate behavior with identical 'result' variable names

>
> I noticed some odd behavior with the accumulate function.  I've got
> two
> very similar rules
>
> 1) validates a string based on a fact and asserts an error fact if the
> string is incorrect
> 2) validates a string based on a fact and asserts a different fact
> which is
> used to correct the string later
>
> I used the accumulate function to accomplish this, because one of any
> possible values for this 'string' are considered to be acceptable.
> Since
> the two rules had minute differences, I copied the rule text,
> changed the
> name, and changed the minor details.  I left the accumulate
> variable the
> same in both rules, and it was named ?result.
>
> rule 1 accumulate:
>   ?someList <- (accumulate (bind ?result (create
> $))                     ;;
> initializer
>                (bind ?result (create$ ?result (...str from ?
> fact...)))  ;;
> action
>                ?
> result                                                  ;;
> result
>                (SOME-FACT-NAME ?fact
>                  &:(...condition1...)
>                  &:(...condition2...)
>                )
>
> rule 2 accumulate:
>   ?someList <- (accumulate (bind ?result (create
> $))                     ;;
> initializer
>                (bind ?result (create$ ?result (...str from ?
> fact...)))  ;;
> action
>                ?
> result                                                  ;;
> result
>                (SOME-FACT-NAME ?fact
>                  &:(...condition1...)
>                  &:(...condition2...)
>                  &:(...condition3...)
>                )
>
> The first rule worked fine, and generated its error fact.  However, I
> noticed that the 2nd accumulate function seemed to be matching on
> facts
> that it should not have, and firing.  The condition 1 and condition
> 2 were
> filtering just fine, but the 3rd condition was not filtering out
> what it
> should have been.  It was funny, because I even placed the same
> condition 3
> check on the RHS of the rule and they would print out FALSE,
> meaning that
> the accumulate should have not even matched the fact that made it
> through.
>
> After scratching my head for a while and trying a bunch of random
> stuff, I
> found that the problem resolved itself when I changed these
> variable names
> to be distinct.  IE, instead of two nearly identical rules with nearly
> identical accumulate functions in which the result variables were
> named the
> same - ?result, I changed the names to the equivalent of ?result_a and
> ?result_b and this problem went away.  It's like the second accumulate
> function was already finding the result variable that was generated
> by the
> first accumulate, and automatically plopping the contents into the
> second
> ?someList.
>
> I'm thinking this is a Jess bug, but I am not positive about that
> (I am
> pretty new to Jess).  I am using Jess 7.0 as well (not sure what
> build), so
> I suppose it also could have been corrected since then.  Hopefully
> this
> example is enough to illustrate what's happening, as I have already
> rambled
> on for a while now.  If more detail is required, I will have to
> replicate
> the problem differently since the actual code is my company's
> property.
>
> .
>
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