[rules-users] Partial Unification / Derivation of Facts?

[JohnnyCaimbridge]

NOTE: Reposted because I only just subscribed to the mailing list.

Hello, 

I have a set of Fact types which represent factors matched and used
throughout the other rules.  Each of these Fact types may be derived in a
variety of mutually exclusive ways--ie based on the line of business or
other factors.  The rules are all well-defined for these Facts.  Something
like this: 

declare FactorType1 
   value : BigDecimal 
end 

rule "FactorType1" 
when 
   LineOfBusiness( this == LineOfBusiness.LOB1 ) 
   // some other conditions 
   $prms : Params() // ***provisional*** where to specify needed context
dependent parameters? see below 
then 
   BigDecimal value = new BigDecimal("0"); 
   // ... determine value based on conditions and $prms 
   insert( new FactorType1(value) ); 
end 

// <some other mutually exclusive rules to derive FactorType1 here>

The problem is that in the rules which match these Facts, there are many
context dependent (ie *always* unique to that particular rule) parameters
which must be "passed" to the derivation of those Facts.  I'm referring to
these as "Params" above.  Now, a rule that uses FactorType1: 

rule "a rule that uses FactorType1" 
when 
   // some conditions 
   FactorType1( $value ) 
   $prms : Params(prm1,prm2,prm3,...) // ***provisional*** how to indicate
that FactorType1 should use these parameters in its derivation? 
then 
   // perform some calculation with $value 
end 

The parameters which these Facts use cannot be asserted as Facts themselves. 
They are unique to the rules which match on the FactorTypes, so that would
mean I'd need a duplicate rule for every rule that uses a FactorType (even
with "rule inheritance", this is excessive). 

It's almost as if I need to specify a "partial derivation" or "partial
unification" of the Fact type, which is only asserted once a rule indicates
that it is providing the "unbound" portion of the derivation.  I understand
queries can be used for some sort of partial unification, but I have no clue
how to apply them to my problem and I can't find any good examples or
documentation on their usage/behavior. 

Thanks in advance  



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