[rules-users] Rules to detect states in an object graph?!?

[Steven Williams]

Hi Michael,

To do the opposite approach (where the relationship is navigable from the
parent only) you can use the following:

when
        c : Child ( age > 18 )
        Parent ( children contains c, type == "SMURF" )

Of course this requires either

   - the child object in the children collection to be the same as the
   asserted child object or
   - the equals/hashcode method to be implemented appropriately in Child

cheers
Steve

On 1/24/07, Anstis, Michael (M.) <manstis1 at ford.com> wrote:
>
>  Sorry, me again,
>
> I'm putting together some prototype rules that operate on related objects
> in a graph of objects.
>
> I'm adding all objects individually to working memory and then checking
> the objects are related in the rule to ensure only valid combinations are
> selected; for example:-
>
> //Java code
> parent.addChild(child)
> wm.assertObject(parent);
> wm.assertObject(child);
>
> //Rule
> rule "Adult smurfs"
> when
>         c : Child ( age > 18, p : parent )
>         Parent ( parentId == ( p.parentId ), type == "SMURF" )
> then
>         System.out.println("Smurf " + p.getName() + " is " + c.getAge() +
> " years old."
> end
>
> rule "Adult clangers"
> when
>         c : Child ( age > 18, p : parent )
>         Parent ( parentId == ( p.parentId ), type == "CLANGER" )
> then
>         System.out.println("Clanger " + p.getName() + " is " + c.getAge()
> + " years old."
> end
>
> This requires that the parent-child relationship is navigable from the
> child end of the relationship -- child.getParent().
>
> What other approaches does anyone else use to implement rules that span
> related objects?
>
> With kind regards,
>
> Michael Anstis
> -------------------------------------------
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>


-- 
Steven Williams

Supervising Consultant

Object Consulting
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