[rules-users] Why Using "from" Always Return A New Fact?

[Swindells, Thomas]

Drools doesn't know if $p.address.state has changed or not, all it knows is that $p has changed - it has to assume that everything within $p has changed (including all the states).

Thomas

> -----Original Message-----
> From: rules-users-bounces at lists.jboss.org [mailto:rules-users-
> bounces at lists.jboss.org] On Behalf Of hyjshanghai
> Sent: 19 January 2011 10:40
> To: rules-users at lists.jboss.org
> Subject: Re: [rules-users] Why Using "from" Always Return A New Fact?
>
>
> Thank you. I understand it now:
> In the 2nd rule:
> modify($p) => evaluate the 2nd rule again => re-iterate $p.address with
> "from", so that Drools engine can know if there is any change in $p.address
> compared with previous evaluation.
>
> Also, the above modify($p) also triggers evaluation of the 1st rule.
>
> Then, why "when the second rule fires, it deactivates the first rule." as
> the document says?
> I think nobody modifies $p.address.state. So the existing activation for the
> 1st rule should still hold. Why the 1st rule is not fired?
> --
> View this message in context: http://drools-java-rules-
> engine.46999.n3.nabble.com/Why-Using-from-Always-Return-A-New-Fact-
> tp2286393p2286492.html
> Sent from the Drools - User mailing list archive at Nabble.com.
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