Function call in LHS

[BINET JEAN-BAPTISTE]

Hello,

I am new to Drools. I have downloaded and installed Drools 4.0.7.
After having read the documentation, I saw that it is possible to create function in the .drl file.
I succeed in creating a function, calling it in the LHS with eval() instruction or in the RHS.
But, is it possible to call a function in the LHS out of an eval() ? For example, I would like to use
a pattern such as :
$tmp : MyClass( name == MyFunction() )

Thanks in advance.

Regards.

JB

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[Mark Proctor]

only inside an eval or return value.

Mark
BINET JEAN-BAPTISTE wrote:

Hello,

I am new to Drools. I have downloaded and installed Drools 4.0.7.
After having read the documentation, I saw that it is possible to create function in the .drl file.
I succeed in creating a function, calling it in the LHS with eval() instruction or in the RHS.
But, is it possible to call a function in the LHS out of an eval() ? For example, I would like to use
a pattern such as :
$tmp : MyClass( name == MyFunction() )

Thanks in advance.

Regards.

JB

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[Costello, Robert]

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I’m having a hard time understanding the syntax in the conditional or left hand side of the DRL.  Is it acceptable to use dot notation in the LHS?  Is there a better way to compare fields on different objects?

 

In the example below, I get an error “Unable to find class $d1.  What limitations are there syntactically on the left hand side?  Any help would be greatly appreciated.  I have looked at all the examples and have googled the problem and don’t seem to find the answer.

 

package com.rules

 

#list any import classes here.

import com.validate.Date1

import com.validate.Date2

import java.util.Date

 

#declare any global variables here

 

rule "Your First Rule"

   

      when

      $d1 : Date1()    

      $d2 : Date2()

      $d2 : Date2(beginDate > $d1.getEndDate)

      then

            #actions

            System.out.println("do something");

end

 

Best regards,

 

Robert Costello

 

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[Scott Reed-3]

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Try this:

rule "Your First Rule"

   

      when

      $d1 : Date1( $end1: endDate )    

      $d2 : Date2()

      $d2 : Date2( beginDate > $end1 )

      then

            #actions

            System.out.println("do something");

end

Costello, Robert wrote:

I’m having a hard time understanding the syntax in the conditional or left hand side of the DRL.  Is it acceptable to use dot notation in the LHS?  Is there a better way to compare fields on different objects?

 

In the example below, I get an error “Unable to find class $d1.  What limitations are there syntactically on the left hand side?  Any help would be greatly appreciated.  I have looked at all the examples and have googled the problem and don’t seem to find the answer.

 

package com.rules

 

#list any import classes here.

import com.validate.Date1

import com.validate.Date2

import java.util.Date

 

#declare any global variables here

 

rule "Your First Rule"

   

      when

      $d1 : Date1()    

      $d2 : Date2()

      $d2 : Date2(beginDate > $d1.getEndDate)

      then

            #actions

            System.out.println("do something");

end

 

Best regards,

 

Robert Costello

 

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[Scott Reed-3]

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Oops, try this:

rule "Your First Rule"

   

      when

          Date1( $end1: endDate )

          Date2( beginDate > $end1 )

      then

            #actions

            System.out.println("do something");

end

Scott Reed wrote:

Try this:

rule "Your First Rule"

   

      when

      $d1 : Date1( $end1: endDate )    

      $d2 : Date2()

      $d2 : Date2( beginDate > $end1 )

      then

            #actions

            System.out.println("do something");

end

Costello, Robert wrote:

I’m having a hard time understanding the syntax in the conditional or left hand side of the DRL.  Is it acceptable to use dot notation in the LHS?  Is there a better way to compare fields on different objects?

 

In the example below, I get an error “Unable to find class $d1.  What limitations are there syntactically on the left hand side?  Any help would be greatly appreciated.  I have looked at all the examples and have googled the problem and don’t seem to find the answer.

 

package com.rules

 

#list any import classes here.

import com.validate.Date1

import com.validate.Date2

import java.util.Date

 

#declare any global variables here

 

rule "Your First Rule"

   

      when

      $d1 : Date1()    

      $d2 : Date2()

      $d2 : Date2(beginDate > $d1.getEndDate)

      then

            #actions

            System.out.println("do something");

end

 

Best regards,

 

Robert Costello

 

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[Costello, Robert]

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Wonderful!  Thanks very much for your learned response.  Java syntax, then, is more reserved for the right hand side of the rule, which makes sense, else we would see semi-colons in the LHS. 

 

Thanks again!

 

Robert Costello

Lead Systems Engineer

IMA Performance

E3- 279A

847.286.0910

 

 

-----Original Message-----
From: rules-users-bounces@... [mailto:rules-users-bounces@...] On Behalf Of Scott Reed
Sent: Monday, July 14, 2008 10:02 AM
To: Rules Users List
Subject: Re: [rules-users] LHS Conditional Syntax for drl - date comparisonwith objects

 

Oops, try this:

rule "Your First Rule"

   

      when

          Date1( $end1: endDate )

          Date2( beginDate > $end1 )

      then

            #actions

            System.out.println("do something");

end

Scott Reed wrote:

Try this:

rule "Your First Rule"

   

      when

      $d1 : Date1( $end1: endDate )    

      $d2 : Date2()

      $d2 : Date2( beginDate > $end1 )

      then

            #actions

            System.out.println("do something");

end

Costello, Robert wrote:

I’m having a hard time understanding the syntax in the conditional or left hand side of the DRL.  Is it acceptable to use dot notation in the LHS?  Is there a better way to compare fields on different objects?

 

In the example below, I get an error “Unable to find class $d1.  What limitations are there syntactically on the left hand side?  Any help would be greatly appreciated.  I have looked at all the examples and have googled the problem and don’t seem to find the answer.

 

package com.rules

 

#list any import classes here.

import com.validate.Date1

import com.validate.Date2

import java.util.Date

 

#declare any global variables here

 

rule "Your First Rule"

   

      when

      $d1 : Date1()    

      $d2 : Date2()

      $d2 : Date2(beginDate > $d1.getEndDate)

      then

            #actions

            System.out.println("do something");

end

 

Best regards,

 

Robert Costello

 

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rules-users mailing list

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