[rules-users] Unsubscribe
Deepak Gmail
angeshwar at gmail.com
Tue Jun 4 12:25:26 EDT 2013
On 4 Jun 2013, at 17:00, rules-users-request at lists.jboss.org wrote:
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> Today's Topics:
>
> 1. ClassCastException due to binding (bdolbeare)
> 2. Re: Setting a value in LHS (Michael Anstis)
> 3. Re: ClassCastException due to binding (Davide Sottara)
> 4. Re: Setting a value in LHS (Stephen Masters)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 4 Jun 2013 08:12:09 -0700 (PDT)
> From: bdolbeare <bdolbeare at yahoo.com>
> Subject: [rules-users] ClassCastException due to binding
> To: rules-users at lists.jboss.org
> Message-ID: <1370358729183-4024115.post at n3.nabble.com>
> Content-Type: text/plain; charset=us-ascii
>
> We have a need to support binds for conditional or elements so that we can
> describe why a rule fired in the then clause of a rule. The following DRL
> is a simple example of what we are trying to do. There are two versions of
> our rule in the DRL:
>
> *rule "WORKING: find with or"*: works but only because the first variable
> we try to bind in the or expression is of type "target" which is a super
> class of the other elements in the or expression.
>
> *rule "BROKEN: find with or"*: causes a class cast exception when the
> "bar" pattern is matched because the then clause tries to store the bar
> object in handle "x" which it thinks is of type "foo".
>
> Is there a way to define the object type for the bind variable?
>
> Is there any other way to make something like this work?
>
>
>
> package tests
>
> import org.apache.log4j.Logger;
>
> global Logger log
>
> declare target
> notreal : boolean
> end
>
> declare foo extends target
> foovalue : String
> end
>
> declare bar extends target
> barvalue : String
> end
>
> rule "insertdata"
> when
> then
> insert(new foo(false, "a"));
> insert(new bar(false, "b"));
> end
>
> rule "WORKING: find with or"
> when
> ( or x: target(notreal)
> x: foo(foovalue == "a")
> x: bar(barvalue == "b")
> )
> then
> log.info("i found object: " + x);
> end
>
> rule "BROKEN: find with or"
> when
> ( or
> x: foo(foovalue == "a")
> x: bar(barvalue == "b")
> )
> then
> log.info("i found object: " + x);
> end
>
>
>
> Exception executing consequence for rule "find with or" in tests:
> java.lang.ClassCastException: tests.bar cannot be cast to tests.foo
> at
> org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
> at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1283)
> at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1209)
> at org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1442)
> at
> org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:710)
> at
> org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:674)
> at
> org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:230)
> at
> org.drools.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:278)
> at tests.DroolsTest.testStateless(DroolsTest.java:120)
> at tests.DroolsTest.runTest(DroolsTest.java:74)
> at tests.DroolsTest.main(DroolsTest.java:59)
> Caused by: java.lang.ClassCastException: tests.bar cannot be cast to
> tests.foo
> at
> tests.Rule_find_with_or_411ee1c99de54340945b2b707ad0a576DefaultConsequenceInvoker.evaluate(Unknown
> Source)
> at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1273)
> ... 9 more
>
>
>
> --
> View this message in context: http://drools.46999.n3.nabble.com/ClassCastException-due-to-binding-tp4024115.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 4 Jun 2013 16:33:11 +0100
> From: Michael Anstis <michael.anstis at gmail.com>
> Subject: Re: [rules-users] Setting a value in LHS
> To: "stephen.masters" <stephen.masters at me.com>, Rules Users List
> <rules-users at lists.jboss.org>
> Message-ID:
> <CAAG9P0uZO_-sskN_1V1uQFXzWuAxCosx=v+i+SVfZ0VHysQKjQ at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> This would need to be provided by the tooling; I don't think it's something
> that's even remotely possible at runtime (unless you stored the field name
> in a Fact and used reflection on the RHS).
>
> That said (and you're going to guess my next comment) this is not provided
> in the guided editors. Depending on how complex your DSLs are and whether
> users need to combine DSL Sentences; IDK if a "cheat" works:
>
> [when]Do something with {field} and {value}=$f : Fact({field}=={value} then
> $f.{field} = {value}
>
> I've not tried it; nor know whether it fits your requirements.. but a hack
> worth trying?
>
>
> On 3 June 2013 17:40, stephen.masters <stephen.masters at me.com> wrote:
>
>> Hi folks,
>>
>> Is there a decent way to set a value in the LHS of a rule so that it's
>> available in the RHS?
>>
>> Reason being I have a DSL driving the guided rules editor which will pluck
>> out the value of a field, where the name of that field is driven by a drop
>> down menu enumeration.
>>
>> A change I now have would be a lot easier if I could assign a string to a
>> variable in the LHS, which could be read by the RHS. Otherwise I might need
>> to extend the RHS DSLs to include the same enumeration as the LHS. Which
>> looks a bit redundant for a business user wondering why the need to write
>> the same thing twice.
>>
>> Any thoughts?
>>
>> Steve
>>
>>
>>
>>
>> Sent from Samsung Mobile
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
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> ------------------------------
>
> Message: 3
> Date: Tue, 04 Jun 2013 17:50:58 +0200
> From: Davide Sottara <dsotty at gmail.com>
> Subject: Re: [rules-users] ClassCastException due to binding
> To: rules-users at lists.jboss.org
> Message-ID: <51AE0CE1.5060808 at gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> "Polymorphic bindings" are not supported, the fact that it's not
> reported at compilation time,
> but only throws an exception at runtime, is a bad bug (I'll open a ticket)
>
> This said, you can split your rule in two rules - which is what Drools
> would do anyway:
>
> rule r1 when $x : Foo() then .. end
> rule r2 when $x : Bar() then .. end
>
> I'd also encourage you to follow java conventions, using capital letters
> for declared types.
>
> And there may be various alternatives to "describe why a rule fired",
> both in and out the RHS of a rule.
> To cite some, using AgendaEventListeners or "drools.getActivation()" in
> the RHS.
> Davide
>
>
> On 06/04/2013 05:12 PM, bdolbeare wrote:
>> We have a need to support binds for conditional or elements so that we can
>> describe why a rule fired in the then clause of a rule. The following DRL
>> is a simple example of what we are trying to do. There are two versions of
>> our rule in the DRL:
>>
>> *rule "WORKING: find with or"*: works but only because the first variable
>> we try to bind in the or expression is of type "target" which is a super
>> class of the other elements in the or expression.
>>
>> *rule "BROKEN: find with or"*: causes a class cast exception when the
>> "bar" pattern is matched because the then clause tries to store the bar
>> object in handle "x" which it thinks is of type "foo".
>>
>> Is there a way to define the object type for the bind variable?
>>
>> Is there any other way to make something like this work?
>>
>>
>>
>> package tests
>>
>> import org.apache.log4j.Logger;
>>
>> global Logger log
>>
>> declare target
>> notreal : boolean
>> end
>>
>> declare foo extends target
>> foovalue : String
>> end
>>
>> declare bar extends target
>> barvalue : String
>> end
>>
>> rule "insertdata"
>> when
>> then
>> insert(new foo(false, "a"));
>> insert(new bar(false, "b"));
>> end
>>
>> rule "WORKING: find with or"
>> when
>> ( or x: target(notreal)
>> x: foo(foovalue == "a")
>> x: bar(barvalue == "b")
>> )
>> then
>> log.info("i found object: " + x);
>> end
>>
>> rule "BROKEN: find with or"
>> when
>> ( or
>> x: foo(foovalue == "a")
>> x: bar(barvalue == "b")
>> )
>> then
>> log.info("i found object: " + x);
>> end
>>
>>
>>
>> Exception executing consequence for rule "find with or" in tests:
>> java.lang.ClassCastException: tests.bar cannot be cast to tests.foo
>> at
>> org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
>> at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1283)
>> at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1209)
>> at org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1442)
>> at
>> org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:710)
>> at
>> org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:674)
>> at
>> org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:230)
>> at
>> org.drools.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:278)
>> at tests.DroolsTest.testStateless(DroolsTest.java:120)
>> at tests.DroolsTest.runTest(DroolsTest.java:74)
>> at tests.DroolsTest.main(DroolsTest.java:59)
>> Caused by: java.lang.ClassCastException: tests.bar cannot be cast to
>> tests.foo
>> at
>> tests.Rule_find_with_or_411ee1c99de54340945b2b707ad0a576DefaultConsequenceInvoker.evaluate(Unknown
>> Source)
>> at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1273)
>> ... 9 more
>>
>>
>>
>> --
>> View this message in context: http://drools.46999.n3.nabble.com/ClassCastException-due-to-binding-tp4024115.html
>> Sent from the Drools: User forum mailing list archive at Nabble.com.
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 04 Jun 2013 16:59:48 +0100
> From: Stephen Masters <stephen.masters at me.com>
> Subject: Re: [rules-users] Setting a value in LHS
> To: Michael Anstis <michael.anstis at gmail.com>, Drools List
> <rules-users at lists.jboss.org>
> Message-ID: <15BB52DC-E304-483F-9BA5-274897C59B8F at me.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Thanks for the cheat idea Mike. I wasn't really expecting any help from the tooling itself. Just hoping that there might be some trickery within the DSL that I could try, to generate some code which would set up a variable for me.
>
> Unfortunately I do need to combine LHS sentences and multiple RHS sentences, so your idea isn't really an option in this case. :(
>
> As it is I have created a little enumeration in the RHS sentence, and it's not looking too bad. At least, with some selective wording, it doesn't look completely redundant!
>
> Steve
>
>
>
> On 4 Jun 2013, at 16:33, Michael Anstis <michael.anstis at gmail.com> wrote:
>
>> This would need to be provided by the tooling; I don't think it's something that's even remotely possible at runtime (unless you stored the field name in a Fact and used reflection on the RHS).
>>
>> That said (and you're going to guess my next comment) this is not provided in the guided editors. Depending on how complex your DSLs are and whether users need to combine DSL Sentences; IDK if a "cheat" works:
>>
>> [when]Do something with {field} and {value}=$f : Fact({field}=={value} then $f.{field} = {value}
>>
>> I've not tried it; nor know whether it fits your requirements.. but a hack worth trying?
>>
>>
>> On 3 June 2013 17:40, stephen.masters <stephen.masters at me.com> wrote:
>> Hi folks,
>>
>> Is there a decent way to set a value in the LHS of a rule so that it's available in the RHS?
>>
>> Reason being I have a DSL driving the guided rules editor which will pluck out the value of a field, where the name of that field is driven by a drop down menu enumeration.
>>
>> A change I now have would be a lot easier if I could assign a string to a variable in the LHS, which could be read by the RHS. Otherwise I might need to extend the RHS DSLs to include the same enumeration as the LHS. Which looks a bit redundant for a business user wondering why the need to write the same thing twice.
>>
>> Any thoughts?
>>
>> Steve
>>
>>
>>
>>
>> Sent from Samsung Mobile
>>
>> _______________________________________________
>> rules-users mailing list
>> rules-users at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/rules-users
>
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