[rules-dev] A dazzling feature - not in Drools!

[Wolfgang Laun]

I am surprised, all the more so because (cf. Expert):

 "Each rule has a salience attribute that can be assigned an integer *number
*,"

This does not event remotely indicate that you can use an
*expression*involving bound variables.

If it isn't documented, nobody will use it. Being in front of the when part
where the bindings occur, it is counter-intuitive to other bound variable
references, and so I didn't even try.

However: good to know, and thanks!

-W


On 26 August 2010 15:21, Edson Tirelli <tirelli at post.com> wrote:
>     Wolfgang,
>     Not sure I understand what you mean, but Drools supports dynamic
> salience:
> rule "fire in rank order 1,2,..."
>       salience( -$rank )
> when
>       Element( $rank : rank,... )
>       ...
> then
>      ...
> end
>     Edson
>
> 2010/8/26 Wolfgang Laun <wolfgang.laun at gmail.com>
>>
>> Just FYI, but who knows ;-)
>>
>> Our proprietary vintage RBS has a feature is (admittedly) rarely used
>> but could come in handy, every now and then.
>>
>> Given this class
>>
>>   class Element {
>>       int rank; // rank > 0
>>   }
>>
>> and to fire a rule in ascending rank order, you can write (using
>> modified Drools syntax)
>>
>> rule "fire in rank order 1,2,..."
>> when
>>       Element( $rank : rank,... )
>>       // ...
>> salience -$rank    ### <=
>> then
>>      // ...
>> end
>>
>> The dynamically set salience does all the work. (Of course, you can
>> achieve the same order
>> in Drools easily enough.)
>>
>> This is possible since salience is a value that must be carried over
>> into the activation.
>> There is at least one other rule attribute that shares this property,
>> but I'm not sure
>> whether anything useful can be done with dynamic agenda groups.
>>
>> Cheers
>> -W
>> _______________________________________________
>> rules-dev mailing list
>> rules-dev at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-dev
>
>
>
> --
>   Edson Tirelli
>   JBoss Drools Core Development
>   JBoss by Red Hat @ www.jboss.com
>
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>
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