Re: [rules-users] Trivial rule with condition in RHS won't compile, help please
Ok, I found http://n3.nabble.com/Strange-MVEL-error-td62055.html#a62055 which indicates that expressions are disabled in mvel RHS. I understand good intentions, but I **need** this expression for this particular situation. Anybody know some what to turn this back on? Also, when I try wrap the RHS in a function, that also fails. I'm guessing because I declare dialect mvel for the entire file. If this is why function fails to compile with an if-statement, this must be a bug. -- View this message in context: http://n3.nabble.com/Trivial-rule-with-condition-in-RHS-won-t-compile-help-please-tp67458p67472.html Sent from the Drools - User mailing list archive at Nabble.com. ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] Trivial rule with condition in RHS won't compile, help please
I would assume that you're trying to test out rule writing and see
what works and what doesn't. I don't believe you can use if
statements in the RHS.
Normally, anytime you want to use if statements inside the RHS, it's
a sure sign that you should move it to the LHS and create separate
rules.
You can actually make your rule even simpler:
rule test
dialect mvel
when
//empty LHS automatically implies true
then
System.out.pritln(***)
end
Cheers,
Chris
On Dec 3, 2009, at 11:43 AM, Barry Kaplan wrote:
The following rule:
rule test dialect mvel
when
eval(true)
then
if (true) {
System.out.println(***)
}
end
Fails with:
java.lang.RuntimeException: Unable to build expression for
'consequence':
was expecting type: java.lang.Object; but found type: void 'if
(true) {
System.out.println(***)
}
true
' : [Rule name='test']
I can't for the live of me figure out what mvel is bitching about.
Note that the following does compile:
rule test dialect mvel
when
eval(true)
then
//if (true) {
System.out.println(***)
//}
end
--
View this message in context:
http://n3.nabble.com/Trivial-rule-with-condition-in-RHS-won-t-compile-help-please-tp67458p67458.html
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[rules-users] Trivial rule with condition in RHS won't compile, help please
The following rule:
rule test dialect mvel
when
eval(true)
then
if (true) {
System.out.println(***)
}
end
Fails with:
java.lang.RuntimeException: Unable to build expression for 'consequence':
was expecting type: java.lang.Object; but found type: void 'if (true) {
System.out.println(***)
}
true
' : [Rule name='test']
I can't for the live of me figure out what mvel is bitching about.
Note that the following does compile:
rule test dialect mvel
when
eval(true)
then
//if (true) {
System.out.println(***)
//}
end
--
View this message in context:
http://n3.nabble.com/Trivial-rule-with-condition-in-RHS-won-t-compile-help-please-tp67458p67458.html
Sent from the Drools - User mailing list archive at Nabble.com.
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Re: [rules-users] Trivial rule with condition in RHS won't compile, help please
Greg Barton wrote: You can use them in the RHS, but just with java dialect. This is inconsistent. If they can be used in java, then they should not be disabled for mvel. -- View this message in context: http://n3.nabble.com/Trivial-rule-with-condition-in-RHS-won-t-compile-help-please-tp67458p67488.html Sent from the Drools - User mailing list archive at Nabble.com. ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
Re: [rules-users] Trivial rule with condition in RHS won't compile, help please
You can use them in the RHS, but just with java dialect. The RHS code should
then be passed through with no modification.
And there are occasional reasons why you would want to test conditions in the
RHS (optimization, mostly) but should be avoided most of the time.
--- On Thu, 12/3/09, CK chris...@gmail.com wrote:
From: CK chris...@gmail.com
Subject: Re: [rules-users] Trivial rule with condition in RHS won't compile,
help please
To: Rules Users List rules-users@lists.jboss.org
Date: Thursday, December 3, 2009, 1:49 PM
I would assume that you're trying to
test out rule writing and see
what works and what doesn't. I don't
believe you can use if
statements in the RHS.
Normally, anytime you want to use if statements inside
the RHS, it's
a sure sign that you should move it to the LHS and create
separate
rules.
You can actually make your rule even simpler:
rule test
dialect mvel
when
//empty LHS automatically implies true
then
System.out.pritln(***)
end
Cheers,
Chris
On Dec 3, 2009, at 11:43 AM, Barry Kaplan wrote:
The following rule:
rule test dialect mvel
when
eval(true)
then
if (true) {
System.out.println(***)
}
end
Fails with:
java.lang.RuntimeException: Unable to build expression
for
'consequence':
was expecting type: java.lang.Object; but found type:
void ' if
(true) {
System.out.println(***)
}
true
' : [Rule name='test']
I can't for the live of me figure out what mvel is
bitching about.
Note that the following does compile:
rule test dialect mvel
when
eval(true)
then
// if (true) {
System.out.println(***)
// }
end
--
View this message in context:
http://n3.nabble.com/Trivial-rule-with-condition-in-RHS-won-t-compile-help-please-tp67458p67458.html
Sent from the Drools - User mailing list archive at
Nabble.com.
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Re: [rules-users] Trivial rule with condition in RHS won't compile, help please
Well, technically you choose a different dialect because you want different functionality, so consistency isn't a requirement. I do agree that the difference is not intuitive. I'm not sure why they're disabled in mvel. Dev d00ds? If the reason is just to enforce the you shouldn't have conditions in the RHS pattern then I don't think that's sufficient. --- On Thu, 12/3/09, Barry Kaplan grou...@memelet.com wrote: From: Barry Kaplan grou...@memelet.com Subject: Re: [rules-users] Trivial rule with condition in RHS won't compile, help please To: rules-users@lists.jboss.org Date: Thursday, December 3, 2009, 2:07 PM Greg Barton wrote: You can use them in the RHS, but just with java dialect. This is inconsistent. If they can be used in java, then they should not be disabled for mvel. -- View this message in context: http://n3.nabble.com/Trivial-rule-with-condition-in-RHS-won-t-compile-help-please-tp67458p67488.html Sent from the Drools - User mailing list archive at Nabble.com. ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users ___ rules-users mailing list rules-users@lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users
