[rules-users] Help -- Conditional Logic in DRL

[Greg Barton]

Note to drools devs: I didn't put the original poster up to this. :)

Globals should be considered immutable, so shouldn't be used in this way. You could do it with an object asserted in working memory, though.

Just as good, though, you can use this kind of pattern to replicate else logic:

rule "EverythingMatches"
when
  Condition0
  Condition1
  Condition2
then
  ...
end

rule "ElseAtCondition2"
when
  Condition0
  Condition1
  !Condition2
then
  ...
end

rule "ElseAtCondition1"
when
  Condition0
  !Condition1
then
  ...
end

rule "ElseAtCondition0"
when
  !Condition0
then
  ...
end

--- On Mon, 6/15/09, Scott Reed <sreed at avacoda.com> wrote:

> From: Scott Reed <sreed at avacoda.com>
> Subject: Re: [rules-users] Help -- Conditional Logic in DRL
> To: "Rules Users List" <rules-users at lists.jboss.org>
> Date: Monday, June 15, 2009, 10:19 PM
> Looks like 5 rules with a global flag
> might work:
> 
> global boolean flag = false;
> 
> rule "name1"
> when
>   (condition1 == true )
>   (flag == false)
> then
>   consequence1();
>   flag = true;
> end
> 
> ...
> 
> rule "name5"
> when
>   (condition5 == true )
>   (flag == false)
> then
>   consequence5();
>   flag = true;
> end
> 
> Does that work for you?
> 
> Vishy [6/15/2009 11:06 PM] wrote:
> > Hi All,
> >
> > I am new to drools...and am trying to figure out as to
> how I can
> > represent the following logic in a DRL file.
> >
> > if (condition1) {
> >
> >   if (condition2) {
> >
> >   } else if (condition3) {
> >
> >   } else if (condition 4) {
> >
> >   } else if (condition 5) {
> >
> >   }
> >
> > }
> >
> > In DSL, a typical rule is represented as follows:
> >
> > rule "name"
> >
> > when
> >   condition is true
> > then
> >   consequence
> >
> > end
> >
> > How can I represent the above mentioned if - else
> logic in DSL? Or is
> > it not possible?
> >
> > If it is not, can you please suggest any alternative?
> >
> > Thanks much!!
> > _______________________________________________
> > 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
> https://lists.jboss.org/mailman/listinfo/rules-users
>