[rules-users] Salience

[Swindells, Thomas]

Another way is to have a helper fact to help with the logic.
In our case we have an "Affirmation" class with the tuple (name, subject, value).
However salience does still have a purpose and is still a useful and required tool to order groups of rules - you just have to make sure you don't abuse it.

rule "#1"
when
  $i : Item(type == 1)
then
   modify ($i)
   // do something...
   insert(new Affirmation("ItemProcessed", $i))
end

rule "#2"
when
  $i : Item(type == 2)
then
  modify ($i)
  // do something...
  insert(new Affirmation("ItemProcessed", $i))
end

// to handle other type of Item
rule "#catch-all"
salience -10
when
  $i : Item()
  not Affirmation(name == "ItemProcessed", subject == $i)
then
  modify ($i)
  // do something...
  insert(new Affirmation("ItemProcessed", $i))
end


> -----Original Message-----
> From: rules-users-bounces at lists.jboss.org [mailto:rules-users-
> bounces at lists.jboss.org] On Behalf Of Wolfgang Laun
> Sent: 19 January 2011 18:57
> To: Rules Users List
> Subject: Re: [rules-users] Salience
>
> Either you define a rule covering all "else" cases, which, in your
> case, could be
>
> rule "#catch-all"
> when
> $i : Item(  type != 1 && != 2  )
> then
> retract ($i)
> // do something...
> end
>
> or you do  rely on salience, which, in this case is not quite so "bad
> practice".
>
> It depends:  if the "catch all" is there to detect unexpected data,
> it's ok; if it is there just to cover several cases the programmer is
> too lazy to code in the ordinary way, then it might be considered "bad
> practice".
>
> -W
>
>
>
> On 19 January 2011 19:17, huionn <huionn at gmail.com> wrote:
> >
> > If I have a rule like below:
> >
> > rule "#1"
> > when
> > $i : Item(type == 1)
> > then
> > retract ($i)
> > // do something...
> > end
> >
> > rule "#2"
> > when
> > $i : Item(type == 2)
> > then
> > retract ($i)
> > // do something...
> > end
> >
> > // to handle other type of Item
> > rule "#catch-all"
> > salience -10
> > when
> > $i : Item()
> > then
> > retract ($i)
> > // do something...
> > end
> >
> > As it is known, reliance on salience is bad practice and its order is not
> > guaranteed (as shown in Sudoku example).
> >
> > My question is: what is the simple and good practice to emulate "else" (rule
> > "#catch-all") without reliance on salience? It seems ruleflow is not
> > applicable here as well.
> >
> >
> > Thanks and best regards.
> > --
> > View this message in context: http://drools-java-rules-
> engine.46999.n3.nabble.com/Salience-tp2289179p2289179.html
> > Sent from the Drools - User mailing list archive at Nabble.com.
> > _______________________________________________
> > rules-users mailing list
> > rules-users at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> >
> _______________________________________________
> rules-users mailing list
> rules-users at lists.jboss.org
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