I hope you're not going through all of that trouble just to get the functionality from that concrete example.  You get that for free with Drools' default conflict resolution, which includes "specificity."  Specificity means that rules with the more specific conditions, and all else equal, are fired first.  So between these two rules, only the CheeseSausagePepperoniPepper one fires:

rule "CheeseOnly"
when
p : Pizza( )
t1: Topping( pizza == p, name == "cheese" )
then
System.out.println( "Eating cheese pizza" );
retract( t1 );
retract( p );
end

rule "CheeseSausagePepperoniPepper"
when
p : Pizza( )
t1: Topping( pizza == p, name == "cheese" )
t2: Topping( pizza == p, name == "sausage" )
t3: Topping( pizza == p, name == "pepperoni" )
t4: Topping( pizza == p, name == "pepper" )
then
System.out.println( "Eating cheese sausage pepperoni pepper pizza" );
retract( t4 );
retract( t3 );
retract( t2 );
retract( t1 );
retract( p );
end

See the attached project.

--- On Tue, 9/1/09, Bill Tarr <javatestcase@yahoo.com> wrote:

From: Bill Tarr <javatestcase@yahoo.com>

Subject: [rules-users]  Trouble getting Dynamic Salience working

To: rules-users@lists.jboss.org

Date: Tuesday, September 1, 2009, 7:28 PM

We have a winner!  Many thanks

Michal, hope I can return the favor one day.

salience ( return getSalience4() )

for the record, my function looks something like (after

tempate evaluation):

<pre>

function int getSalience4(){

    int salience = 0;

    if("VALUE"=="VALUE") salience += 1000;

    return salience;

}

</pre>

I think the combination activation-group and dynamic

salience for rule-template projects are pretty useful.

Just for anyone interested, the tempate code looks

something like this:

<pre>

rule "Some Rule_@{row.rowNumber}"

    activation-group "@{PARAM1}-@{PARAM2}"

    salience ( return getSalience@{row.rowNumber}() )

</pre>

where PARAM1 and PARAM2 make up a kind of key. I only want

to execute one rule that matches that key, no matter how

many options there are.

Rules that have additional parameters get higher salience

than rules with less parameters, so here is my function.

<pre>

function int getSalience@{row.rowNumber}(){

    int salience = 0;

    if("@{PARAM3}"=="@{PARAM3}") salience += 1000;

    if("@{PARAM4}"=="@{PARAM4}") salience += 1000;

    return salience;

}

</pre>

A concrete example could be pizza.  So there are 3 types

of pizza, all are grouped in the same activation-group.

cheese, pepperoni

cheese, pepperoni, sausage

cheese, pepperoni, meatball, pepper

Any cheese and pepperoni pizza should could match all these

rules, but more toppings is always better for me.

So cheese, pepperoni, onion, pepper getts a salience of

2000, and is the only rule evaluated.

On Tue Sep 1 18:39:13 EDT 2009, Michal Bali michalbali at

gmail.com  wrote:

does this work?

salience ( return getSalience() )

or this:

salience ( getSalience();)

On Tue, Sep 1, 2009 at 6:50 PM, Bill Tarr <javatestcase

at yahoo.com> wrote:

Possibily just a simple MVEL error, but I've been

struggling for a while

and thought I'd see if anyone could help.

I just want to run a logic test to determine salience

for some rules I am

generating with rules-templates.  Even after making

the logical test "true"

I can't get any of variation to compile.

(true ? "1000" : "0")

**produces**

Unable to build expression for 'salience' : not a

statement, or badly

formed structure

( true ? 1000 : 0)

**produces**

Unable to build expression for 'salience' : invalid

number literal: 1000

salience ( getSalience() )

...

function int getSalience(){return 0;}

**produces**

Unable to build expression for 'salience' :

org.mvel2.util.MethodStub

cannot be cast to java.lang.Class'(

getSalienceNONCDW() )'

Seems like I am missing something simple, but I've

tried many variations on

the above, and have been unable to find any working

examples of using a

logical test in salience, so if anyone has any

direction it would be greatly

appreciated.

Thanks!

Bill

     

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