[rules-users] Rewriting rules

[Wolfgang Laun]

On 9 February 2011 16:49, jwillans2 <james.willans at ceteva.com> wrote:

>
> Hi Wolfgang,
>
> For example, the user may specify something along the lines of:
>
> rule "example"
>  when
>    Object(slot = "value")
>

An java.lang.Object doesn't have a property called "slot".


>  then
>    ..
> end
>
> Minimally we might want to rewrite the rule to strengthen the condition:
>
> rule "example"
>  when
>    Object(slot = "value", id = 125)
>

Let's say you want to check whether
      Item( id == 125 )
and specify 125 only at runtime. Then you can write your rule as
      ItemParam( field == "id", $value: value )
      Item( id == $value )

But I'd prefer using templates and generate simple rules, even at runtime.



>  then
>    ..
> end
>
> Where 125 is not known until runtime.  We may want to handle more complex
> cases where the user refers to "facts" that are conceptually scoped, but we
> may want to rewrite using "from":
>
> rule "example"
>  when
>    $op : ObjectProvider()
>    Object(slot = "value") from op.eval()
>

Again, java.lang.Object is not useful. -- Why don't you simply insert the
objects
contained in ObjectProvider's eval field?

-W


>  then
>    ..
> end
>
> Thanks,
>
> James
>
> --
> View this message in context:
> http://drools-java-rules-engine.46999.n3.nabble.com/Rewriting-rules-tp2458626p2459318.html
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