[rules-dev] Changing a fact's hashCode causes rules not to fire

[Wolfgang Laun]

If I have
   class Type {
      int field;
      setField( int f ){ field = f; }
   }

and do

   modify( $type ){ setField( 42 ) }

where is there a "nested accessor"?

-W

On 23 June 2011 10:24, Mark Proctor <mproctor at codehaus.org> wrote:

> **
> On 23/06/2011 07:03, Wolfgang Laun wrote:
>
> Eeek!
>
> Assume this: A is a field of B is a field of C is a field of D is a...
>
> Object references remain the same, in all objects; I simply modify A, and
> "when you change [A] you are also changing [B], so I must notify the
> engine for [B]" but that's a field of C...  D... E... and so on, until
> 'I' for infinity?!
>
> *It's just a change in some fact object's hashCode that causes this
> problem.*
>
> If you don't want any indexing in your rule engine. If you want indexing,
> you have to notify the engine. Changes to nested accessors have always been
> invisible to the engine. If a nested access changes, you must notify the
> engine of the root fact.
>
> Mark
>
>
> -W
>
>
>
> On 22 June 2011 22:37, Mark Proctor <mproctor at codehaus.org> wrote:
> > As One is a field of Two. When you change One you are also changing Two,
> so
> > you most notify the engine for Two too.
> >
> > MArk
> > On 22/06/2011 14:37, Wolfgang Laun wrote:
> >
> > To avoid misunderstandings: yes, equals() is written according to
> hashCode,
> > i.e., according to the usual Java conventions.
> >
> > If
> >
> >    - an object of class Two contains a member of class One, and
> >    - one object Two and one object One are facts, and
> >    - a rule modifies One, changing its hashCode
> >
> > then
> >
> >    another rule containing the patterns
> >    $one: One()
> >    $two: Two( $x: one == $one )
> >
> > does NOT fire (any more).
> >
> > If you use the constraint
> >    one == $one || != $one
> > the rule will fire, and you can observe that hashCode results for $one
> and
> > $x are the same and that $one.equals( $x ) returns true.
> >
> > Reproduced using 5.1.1 and 5.2.x
> >
> > -W
> >
> >
> >
> >
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