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: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] 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* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> 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: [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>
>[mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>] 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
>>
>>
>>
>>_______________________________________________
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>>[email protected] <mailto:[email protected]>
>>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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