[rules-users] How to check for a variable number of "conditions" ina rule?

[Anstis, Michael (M.)]

Hi Ron,

Have a look at the "Alarms" example for "Collect" in the (4.0.5) manual.

This should give you a good starting point.

Cheers,

Mike

-----Original Message-----
From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Ron Kneusel
Sent: 22 July 2008 23:01
To: rules-users at lists.jboss.org
Subject: [rules-users] How to check for a variable number of
"conditions" ina rule?


Greetings!

I want to create a rule that checks a fact which contains an array to
see if n or more of the elements of that array have a specific value.
The number of elements to check will vary from invocation to invocation
of the rules engine and will likely be added as a global.

I can do this by using a helper function.  Say, for example, I have:

rule "fire_when_testFlags_true"
    when
        eval(testFlags(flags, limit.intValue()));
    then
        System.out.println("Yup, " + limit + " or more flags are
true!");
end

Where flags and limit are both globals.  Then I can define testFlags as:

function boolean testFlags(Flags flags, int threshold) {
    int count = 0;

    for(int i=0; i < flags.getSize(); i++) {
        if (flags.getValue(i)) {
            count++;
            if (count>= threshold) {
                return true;
            }
        }
    }   
    return false;
}

This works but violates the warning not to use a global that isn't
immutable in the LHS of a rule.  Does anyone have an idea about how to
implement a rule that in effect has an arbitrary number of conditions to
be tested?

Ron

_________________________________________________________________
Keep your kids safer online with Windows Live Family Safety.
http://www.windowslive.com/family_safety/overview.html?ocid=TXT_TAGLM_WL
_family_safety_072008
_______________________________________________
rules-users mailing list
rules-users at lists.jboss.org
https://lists.jboss.org/mailman/listinfo/rules-users