9:59 a.m.
Cheese ( name == $p.favouriteFoods.favouriteCheese )
That is a different thing, because a rule engine can only understand the asserted facts
and their direct properties, so where as one is a short cut for a standard variable
constraint, the other in the expression above, would have to be swapped out for a return
value constraint with the expression executed by MVEL. That is also planned. However be
aware that excessive use of deep nested graphs will really just turn drools into a
standard scripting engine.
Mark
Anstis, Michael (M.) wrote:
For what it's worth I like the thought of:-
$p : Person()
Cheese ( name == $p.favouriteCheese )
I like even more:-
$p : Person()
Cheese ( name == $p.favouriteFoods.favouriteCheese ) <-- i.e. object
model navigation
And possibly (subject to constrains such as "must be a Map" - I think
there's a similar requirement for extension of "contains"):-
$p : Person()
Cheese ( name == $p.favouriteFoods["cheese"] )
I'm with Edson (given my limited use) regarding pattern matches - it's
easier for me (as a user) to understand.
I can't say I understand what the cross-product issue is though (I know
"cross-product==bad").
Cheers,
Mike
-----Original Message-----
From: rules-dev-bounces(a)lists.jboss.org
[mailto:rules-dev-bounces@lists.jboss.org] On Behalf Of Edson Tirelli
Sent: 20 March 2007 23:22
To: Rules Dev List
Subject: Re: [rules-dev] sugar
Yes, that is the part that I agreed.... :)
I just would NOT want:
Cheese( name == Person().favouriteCheese )
[]s
Edson
Michael Neale wrote:
> I am not sure about the "danger", but I do like anything that avoids
> extra binding.
> So lets not throw the baby out with the bathwater.
>
> I really like:
> $p : Person()
> Cheese( name == $p.favouriteCheese )
>
> I think that should definately be allowed.
>
>
> On 3/21/07, *Edson Tirelli* <tirelli(a)post.com
> <mailto:tirelli@post.com>> wrote:
>
>
> I think it is a dangerous move.
> It is easy for users to understand that each pattern matches a
> fact:
>
> A( ... )
> B( ... )
> C( ... )
>
> If you start moving patterns to inside other patterns, you risk
>
to
> lose the legibility:
>
> A( b == B( ... ), c == C(...) )
>
> Main problem I see is with cross product abuses:
>
> A( oneb == B(...), thesameb == B(...) )
>
> The above may match the same B as intended, but may also match
> other
> Bs, leading to errors and bugs that will be hard to track.
> I would continue making patterns explicit and not nested.
>
> Although, the object navigability is desired and much waited I
> think:
>
> $b : B(...)
> A( c == $b.c )
>
> Also, there are some cases that we would do good allowing
>
nesting:
> $c : Cheesery( ... )
> $s : List( size < 3 ) from collect( Cheese( type == "stilton" )
>
from
> $c.getCheeses() )
>
> Just my .02 c.
>
> []s
> Edson
>
> Olenin, Vladimir (MOH) wrote:
>
> >Don't have any antlr experience, but I'd say that would be a very
> valuable
> >addition - probably more BAs would be able to pick it up this way
> (without
> >having to fallback on custom DSL)
> >
> >Vlad
> >
> >-----Original Message-----
> >From: rules-dev-bounces(a)lists.jboss.org
> <mailto:rules-dev-bounces@lists.jboss.org>
> >[mailto:rules-dev-bounces@lists.jboss.org
> <mailto:rules-dev-bounces@lists.jboss.org>] On Behalf Of Mark
>
Proctor
> >Sent: 20 March 2007 15:54
> >To: Rules Dev List
> >Subject: Re: [rules-dev] sugar
> >
> >Could also allow:
> >Cheese( name = Person( location == "london").favourCheese )
> >
> >Can also use this to constrain on the fact itself, instead of
> just a field:
> >Person( cheese = Cheese( type == "stilton ) )
> >
> >This could be use in config options:
> >Call( duration < CallConf().minDuration )
> >
> >But as Edson pointed out it is open to abuse and
> misunderstanding, how
> >long till people do:
> >Call( duration < CallConf().maxDuration, duration >
> CallConf().maxDuration )
> >
> >Which is more like doing the following which has cross product
> issues:
> >CallConf( $maxDuration1 : maxDuration )
> >CallConf( $maxDuration2 : maxDuration )
> >Call( duration < ,$maxDuration1 duration > $maxDuration2 )
> >
> >Mark
> >Mark Proctor wrote:
> >
> >
> >>I've been thinking of an idea to make rules more expressive, its
> just
> >>syntax sugar at the parser level, but thought i'd ask feedback -
>
if
> >>anyone with antlr skills wants to make this work, let us know :)
> >>
> >>Instead of doing:
> >>$p : Person($favouriteCheese : favouriteCheese )
> >>Cheese( name == $favouriteCheese )
> >>
> >>We should allow the following:
> >>$p : Person()
> >>Cheese( name == $p.favouriteCheese )
> >>
> >>We could take this further and in places where a pattern is not
> used
> >>elsewhere allow:
> >>Cheese( name == Person().favouriteCheese )
> >>
> >>Mark
> >>
> >>
> >>
> >>_______________________________________________
> >>rules-dev mailing list
> >>rules-dev(a)lists.jboss.org <mailto:rules-dev@lists.jboss.org>
> >>https://lists.jboss.org/mailman/listinfo/rules-dev
> >>
> >>
> >>
> >
> >_______________________________________________
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> > https://lists.jboss.org/mailman/listinfo/rules-dev
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> >
> >
> >
>
>
> --
> Edson Tirelli
> Software Engineer - JBoss Rules Core Developer
> Office: +55 11 3124-6000
> Mobile: +55 11 9218-4151
> JBoss, a division of Red Hat @ www.jboss.com
>
<http://www.jboss.com>
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