Hi,
Just as a (newbie) exercise, I was trying to consider a simplified version of
the "Miss Manners" example (from Drools site).
My simplified version requires:
- Given 4 guests (exactly), try to seat them in a line
- Each pair of adjacent guests should have shared hobies
Now, my question:
Since the number of guests is known in advance (4), I was hoping to write a
simple rule with 4 parameters :
<parameter identifier="guest1">...
<parameter identifier="guest2">...
<parameter identifier="guest3">...
<parameter identifier="guest4">...
(As opposed to the Miss Manners example, where number of guests isn't given
in advance, so you must work pretty hard just to build the tuples).
So I came up with something like this
(all params are of class "Guest"):
< parameter identifier="g1" >
< parameter identifier="g2" >
< parameter identifier="g3" >
< parameter identifier="g4" >
< condition > g1.hasSharedHobies(g2) < / condition >
< condition > g2.hasSharedHobies(g3) < / condition >
< condition > g3.hasSharedHobies(g4) < / condition >
< consequence > System.out.println(g1+g2+g3+g4); < / consequence >
However, I don't like the condition duplication (g1 shares hobies with g2, g2
shares hobies with g3, etc... too much "cut & paste").
Is there a more elegant way to do this ?
I did consider arrays:
< condition > checkLine(g1,g2,g3,g4) < / condition >
Using a function:
boolean checkLine(Guest g1, Guest g2, Guest g3, Guest g4){
Guest[] all={g1,g2,g3,g4};
// ... loop over array and check every adjacent pair
}
Unfortunately, this "array" approach would give horrible performance, because
it doesn't take advantage of the way Rete algorithm works...
I would greatly appreciate other ideas...
Thanks very much.
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