[rules-dev] Rule Parameters/Aliases

[Yoni Mazar]

Hi Mark, 

First of all thanks for the response. Using global variables may be a good
workaround for in/out parameters. 

Our purpose of using named parameters is to differentiate between facts
which may be of the same type but may have different role (without forcing
the rule author to add this logic in the patterns). 

for example - one can write the following rule:

rule "Rule1"
	when
		$anemia: Diagnosis(alias == "anemia")
		$hypertension: Diagnosis(alias == "hypertension")
		
		//business logic here
		Diagnosis (code == "5") from $anemia and 
		Diagnosis (code == "7") from $hypertension		
	then 
		#DO something
end

but this solution is much better since it extracts the alias complexity
outside of the rule:

#declare any global variables here
global java.util.List anemia;
global java.util.List hypertension;

rule "Rule1"
	when
		//business logic here
		Diagnosis (code == "5") from anemia 
		and 
		Diagnosis (code == "7") from hypertension	
	then 
		#DO something
end

this solution will of course force us to introduce the facts twice - once as
normal facts inserted to the working memory and once as globals in order to
allow the parameterization.

will this workaround cause unwanted results (since the facts appear twice)?

Thanks

Yoni

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