[rules-users] Design Question

[Mark Proctor]

Christie, Blair wrote:
>
> Does anyone have any examples of using  the new 'from' element it is 
> now common to pass a Hibernate session as a global, to allow 'from' to 
> pull data from a named Hibernate query.
>
>  
>
> Would it be good design to store the values for a condition in a 
> database so they can be changed without having to go into the .drl file?
>
>  
>
> i.e.
>
> So instead of ..
>
>  
>
>  Rule "free food"
>
>     when
>
>         Food( $food : name == "hamburger" )
>
>         $: Person( favouriteFood == $food )
>
>     then
>
>         System.out.println( $person.getName() + " gets a hamburger" );
>
>     End
>
>  
>
> You would have
>
>  
>
> global Food food //where food is inserted as a global but populated 
> from a db.
>
>  
>
> Rule "free food"
>
>     when
>
>        $food : food
>
>         $person: Person( favouriteFood == $food )
>
>     then
>
>         System.out.println( $person.getName() + " gets a " + 
> $food.getName() );
>
>     End
>
>  
>
> Cheers,
>
>  
>
> Blair
>
No that isn't good, due to indexing. If $food changes value without the 
engine knowing about it, then you get a memory leak. So you have to 
assert the value. Globals really are for immutable vars or containers to 
collect results.
>
>  
>
>  
>
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>
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