[rules-dev] An odd couple of patterns

[Joe White]

Wolfgang I use patterns like that for a data filtering problem and also
for a preferential selection problem. Any time I have two sources of the
same data and I prefer one over the other that pattern allows you to
pick the secondary source when the preferred data doesn't exist. Also
used in cases where we want to execute a different action in the absence
of the second source.

 

It also occurs for us when dealing with a list of objects where we have
two sources for the same type of data and we prefer one data source over
the other, but we don't always get data for the preferred source.. We
use your pattern to make sure the preferred source doesn't exist before
using the secondary source

 

 

Joe 

 

Here is an example from our code. $ebs is a List<Map>. Mapping to your
example the Map is the fact and the combination of BnftInfoCdoe and
BnftCvgeLevelCode would be the field.:

 

  Map(this[BenefitsConsts.BenefitResponseEligibility.BnftInfoCode] ==
'C',

      this[BenefitsConsts.BenefitResponseEligibility.BnftCvgeLevelCode]
== 'IND',

      this[BenefitsConsts.BenefitResponseEligibility.SvcTypeCode] ==
"30",

this[BenefitsConsts.BenefitResponseEligibility.CvgePeriodQlfr] == '25', 

      this[BenefitsConsts.BenefitResponseEligibility.BnftAmt] matches
"0.*") from $ebs

 

not (Map(this[BenefitsConsts.BenefitResponseEligibility.BnftInfoCode] ==
'C',

 
this[BenefitsConsts.BenefitResponseEligibility.BnftCvgeLevelCode] ==
'FAM') from $ebs)

 

From: rules-dev-bounces at lists.jboss.org
[mailto:rules-dev-bounces at lists.jboss.org] On Behalf Of Wolfgang Laun
Sent: Thursday, March 24, 2011 11:07 AM
To: Rules Dev List
Subject: [rules-dev] An odd couple of patterns

 

Has anybody ever seen a situation where a couple of patterns such as

   Fact( field >= 10 )
   not Fact( field > 20 )

was appropriate? This does not match Facts where field isn't between 10
and 20, and so it would seem to be the same as

   Fact( field >= 10 && <= 20 )

but actually it doesn't match any such Fact whenever any other Fact with
field > 20 is around.

Cheers
Wolfgang

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