On 08/06/2012, bdolbeare <bdolbe...@yahoo.com> wrote:
> Can someone explain to me why these two rules behave differently? I
> expected
> that the second rule would produce the same output as the first but it
> seems
> to ignore the first half of the logical or expression. Is this because the
> unification happens before the null checks occur?
>
It's a simple case of the "sorprise" ( sic ;-) ).
A rule containing the Conditional Element "or" is transformed into two
(or more, depending on the number of operands) rules running under the
same name. See the Expert manual.
-W
>
>
> declare Foo
> name : String
> item : Item
> end
> declare Item
> id : long
> end
>
> rule "insert stuff"
> when
> then
> Item item1 = new Item(1);
>
> Foo foo1 = new Foo("foo1", item1);
> insert(foo1);
>
> Foo foo3 = new Foo("foo3", null);
> insert(foo3);
> end
> rule "Unification Test Rule"
> when
> f : Foo ( item != null, $item := item )
> f2 : (
> Foo ( item == null )
> or Foo ( $item := item )
> )
> then
> System.out.println(String.format("%s Fired:\n\tFoo: %s\n\t%s",
> kcontext.getRule().getName(), f, f2));
> end
> rule "Unification Test Rule 2"
> salience -10
> when
> f : Foo ( item != null, $item := item )
> f2 : Foo ( ( item == null ) || ( item != null && $item := item
> ) )
> then
> System.out.println(String.format("%s Fired:\n\tFoo: %s\n\t%s",
> kcontext.getRule().getName(), f, f2));
> end
>
>
> Unification Test Rule Fired:
> Foo: Foo( name=foo1, item=Item( id=1 ) )
> Foo( name=foo3, item=null )
> Unification Test Rule Fired:
> Foo: Foo( name=foo1, item=Item( id=1 ) )
> Foo( name=foo1, item=Item( id=1 ) )
>
> Unification Test Rule 2 Fired:
> Foo: Foo( name=foo1, item=Item( id=1 ) )
> Foo( name=foo1, item=Item( id=1 ) )
>
> --
> View this message in context:
> http://drools.46999.n3.nabble.com/Unification-with-logical-or-question-tp4017826.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
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