[rules-users] Suppressing reciprocal matches

[D Brock]

Thanks Mark, sounds good.  And the hashCode trick works.  Wow, I would have
never thought of that!


Mark Proctor wrote:
> 
> D Brock wrote:
>> I have defined the following rule to detect when duplicate objects (in
>> this
>> example, Widgets) exist.  This always produces two matches, and therefore
>> two messages.  I understand why this occurs, but I would like for only
>> one
>> message to be reported.  I cannot retract one of the widgets after a
>> match
>> b/c all are needed for additional rules matching.  Is the a conventional
>> way
>> for accomplishing the elimination of the reciprocal match?
>>
>> rule "Do not allow duplicate widgets"
>> 	when
>> 		$w : Widget( $name : name )
>> 		Widget( this != $w, name == $name )
>> 	then
>> 		System.out.println( "Duplicate widgets found with name =  " + $name );
>> end
>>   
> We are looking into a new conditional element that can achieve this. The 
> idea is when you use this CE, it ensures only a single permutation will 
> be propagated. In the meantime you can probably try something like:
> 
> $w : Widget( $name : name )
>      Widget( this != $w, hashCode < $w.hashCode, name == $name )
> 
> 
> 
> 
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> 
> 

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