[rules-users] Room to optimize or bug? Unnecessary calls to unused method

[Wolfgang Laun]

@Davide
I had a sentence in the 1st draft of my email that complained about
binding variables being sold as *variables*. Not explaining things
that may have a noticeable impact on the behaviour of the code
your write taking everything in the documentation at face value:
this is ouch, ugh and very argh.

-W


On 13/05/2013, Davide Sottara <dsotty at gmail.com> wrote:
>
> @Wolfgang: "Declarations" in drools are not variables in the sense that
> they "store" the
> value extracted from the bean, but they use internal accessors to read
> it from the bean
> itself. So, in your example, two calls are expected: one when the value
> is read for the != null
> comparison, one when the value is displayed in the RHS.
>
> I'm not sure that this optimization would be easy or even feasible,
> especially considering that
> the performance "penalty" would hardly be noticeable. Unless one has
> stateful getters (ouch..),
> getter with side effects (ugh..) or getters that do expensive internal
> computations on the fly (argh..).
>
> Davide
>
>
>
>
> On 05/12/2013 09:44 PM, Wolfgang Laun wrote:
>> OP states that
>>    rule test1
>>    when
>>         $m: Message( myMessage : message != null )
>>    then
>>    end
>> with
>>     public String getMessage(){
>>         System.out.println("Called getMessage()");
>>         return message;
>>     }
>> displays "Called getMessage()" more than once, which (using 5.5.0) I
>> cannot confirm. However
>>    rule test2
>>    when
>>         $m: Message( myMessage : message != null )
>>    then
>> 	System.out.println( "test2: " );
>>   	System.out.println( "message(1): " + myMessage );
>>    end
>> produces
>>   Called getMessage()
>>   inserted
>>   Called getMessage()
>>   test2:
>>   message(1): Hello
>> which confirms OP's claim that there are redundant calls to getters.
>>
>> -W
>>
>>
>> On 12/05/2013, Mark Proctor <mproctor at codehaus.org> wrote:
>>> The code examples of what you are proposing did not make it to the list.
>>>
>>> Mark
>>> On 12 May 2013, at 12:29, Sonata <plz.write.to at gmail.com> wrote:
>>>
>>>> Hi, I am using 5.5.0.final on jdk7(64bit). To repeat the test, simply
>>>> create
>>>> a new Drools project in Eclipse. Tick the option to create a default
>>>> Hello
>>>> World project. Go to the DroolsTest.java file, edit main() to
>>>>
>>>>
>>>> and edit getMessage() to
>>>>
>>>>
>>>> Next, remove the two rules in Sample.drl, use this simple rule instead
>>>>
>>>>
>>>> Then you can see the output
>>>>
>>>>
>>>> Which means, getMessage() is called 4 times in this simple rule. I
>>>> really
>>>> wonder why. Is this a bug? Some non-optimized routine? An edge case?
>>>>
>>>> Now try this
>>>>
>>>> and the output is
>>>>
>>>>
>>>> Just once. It seems all good. Because getMessage() is needed to call
>>>> once
>>>> to
>>>> check with null, which is very fair to me.
>>>>
>>>> Now something really funny
>>>>
>>>>
>>>> and the output
>>>>
>>>>
>>>>
>>>> An extra call to getMessage() at the end, total 5 times!
>>>>
>>>> TBH, I really only expect calling getMessage() once in all these tests.
>>>> Please put it to my face and tell me my test is so flawed.
>>>>
>>>>
>>>>
>>>> --
>>>> View this message in context:
>>>> http://drools.46999.n3.nabble.com/Room-to-optimize-or-bug-Unnecessary-calls-to-unused-method-tp4023790.html
>>>> Sent from the Drools: User forum mailing list archive at Nabble.com.
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>>>
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