[rules-users] LHS reuse?

[Mark Proctor]

Barry Kaplan wrote:
> I have a set of rules that /all/ contain the following condition...
>
> positionQuantityAllocatedToLegs : 
>         Integer(intValue < position.quantity)
>         from accumulate( StrategyLeg(priority > 1, instrument == equity,
>                                                  longShort ==
> LongShort.LONG, legQuantity : quantity )
>                                                  legsQuantity(legQuantity) )   
>
> ...the only difference being the values for the StrategyLeg. 
>
> It would be very nice if there was some way to create reusable LHS
> constructs, say maybe something like:
>
> positionQuantityAllocatedToLegs : legsAllocation(1, position.quantity,
> LongShort.LONG)
>
> Where 'legsAllocation' is replaced with the condition above. Is there such a
> mechanism, or need I simply live with large amounts of duplication in my
> LHS?
>   
You can use DSLs for this already, which are like sentence templates and 
rules already allow mixed DSL and normal rules. So create a DSLs that 
encompass the shared bits and reuse them in your drl.

It would be nice to see rule extensions and rule "mixins" for code 
reuse. But unless it comes from the community its not going to happen 
any time soon. I'd be happy to chat to anyone on irc on how to do these 
things, if someone has the time and wants to give it a go.
> thanks!
>                                             
>