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 $p has changed (including all the
states).
Thomas
-----Original Message-----
From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-
bounces(a)lists.jboss.org] On Behalf Of hyjshanghai
Sent: 19 January 2011 10:40
To: rules-users(a)lists.jboss.org
Subject: Re: [rules-users] Why Using "from" Always Return A New Fact?
Thank you. I understand it now:
In the 2nd rule:
modify($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?
--
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