3:18 p.m.
Hi,
Please let me know nested loops are possible in drools or not..
Scenario like this needs to be developed
list values : A,B,C,D,E,F..
Need to set 1 in Action if D is after C.
So here i need to loook for D and if got again that list will be iterated
and will check for C.
Have tried this logic without nested loops and it works fine but performance
wise its hitting.
So Kindy let me know whether Nested loops are possible or not..
Thanks
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3:29 p.m.
Determining the truth value of a complex property is best done by writing a
function, e.g.
function isYafterX( List list, Object y, Object y)
and by calling this function in an eval() conditional element.
-W
On 20 July 2012 22:18, salt <writemesaltworth(a)gmail.com> wrote:
Hi,
Please let me know nested loops are possible in drools or not..
Scenario like this needs to be developed
list values : A,B,C,D,E,F..
Need to set 1 in Action if D is after C.
So here i need to loook for D and if got again that list will be iterated
and will check for C.
Have tried this logic without nested loops and it works fine but
performance
wise its hitting.
So Kindy let me know whether Nested loops are possible or not..
Thanks
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3:39 p.m.
Oops, forgot the return type and a typo:
function boolean isYafterX( List list, Object x , Object y)
On 20 July 2012 22:29, Wolfgang Laun <wolfgang.laun(a)gmail.com> wrote:
Determining the truth value of a complex property is best done by
writing a
function, e.g.
function isYafterX( List list, Object y, Object y)
and by calling this function in an eval() conditional element.
-W
On 20 July 2012 22:18, salt <writemesaltworth(a)gmail.com> wrote:
>
> Hi,
>
> Please let me know nested loops are possible in drools or not..
>
> Scenario like this needs to be developed
>
> list values : A,B,C,D,E,F..
>
> Need to set 1 in Action if D is after C.
>
> So here i need to loook for D and if got again that list will be iterated
> and will check for C.
>
> Have tried this logic without nested loops and it works fine but
> performance
> wise its hitting.
>
> So Kindy let me know whether Nested loops are possible or not..
>
> Thanks
>
>
>
>
> --
> View this message in context:
> http://drools.46999.n3.nabble.com/NESTED-LOOPS-Possible-tp4018811.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
> _______________________________________________
> rules-users mailing list
> rules-users(a)lists.jboss.org
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>
12:49 a.m.
Hi Laune,
Thanks for your comments. But i am not allowed to use eval() as that also
might have performance issues. I like to implement this as simple as
possible..
Actually this is my problem,
$order:Order() Transaction() from $order.transaction
if the list contains A,B,C,D,E,F
According to my requirement i will search for D from the list and even after
finding also the loop continues till last element.
So if nested loops possible i can search for C in inner list by skipping the
other loops in the outer list after finding D.
Please let me know whether nested loops are possible.
Thanks for your support.
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3:21 a.m.
On 21/07/2012, salt <writemesaltworth(a)gmail.com> wrote:
Hi Laune,
Thanks for your comments. But i am not allowed to use eval() as that also
might have performance issues.
Who forbids this? Bah.
Actually this is my problem,
$order:Order() Transaction() from $order.transaction
if the list contains A,B,C,D,E,F
Not very lucid.
Please let me know whether nested loops are possible.
There are no "loops" in DRL in the sense you appear to be thinking,
i.e., procedurally.
Here's how to do it:
function boolean cd( List list, Integer c, Integer d ){
int cPos = list.indexOf( c );
return cPos != -1 ? list.subList(cPos+1, list.size()).indexOf d)
!= -1 : false;
}
rule cd
when
$l: List()
Pair( $c: c, $d: d )
eval( cd( $l, $c, $d ) )
then
end
This takes, on the average, 0.000014s (2.80GHz) per evaluation for
random combinations of elements that are actually in the list (and a
little less if one or both aren't contained). List length doesn't
really matter; for a list with 1000 elements the average is 0.000016s.
-W
Thanks for your support.
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9:40 p.m.
do not scoff so quickly, WL. eval() can be a big performance kill, since
eval() condition is always executed during rule evaluation. For example,
if the eval is on a remote invocation that might hang or be sluggish (long
timeout) it can drag the server down.
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1:12 a.m.
Hi Lisa,
to disallow a (programming language) feature is not adequate; most of
the time a feature exists because it is necessary, and when
circumstances suggest its use, use it, rather than get tangled in
loops and hoops of a workaround. True, coding rules might indeed
blacklist "dangerous" features, but ours always permit to make an
exception provided you can justify it.
You point out the possibility of creating slowdowns with "eval", but
with Drools 5.4, you can create all sorts of mischief in a simple
constraint expression, too. Moreover, you have the option of hiding
everything in a getter...
My "bah" is directed at people who forbid rather than educate. I wrote
it after spending 5 or 10 minutes of creating and running a little
benchmark.
Cheers
Wolfgang
On 22/07/2012, lhorton <LHorton(a)abclegal.com> wrote:
do not scoff so quickly, WL. eval() can be a big performance kill,
since
eval() condition is always executed during rule evaluation. For example,
if the eval is on a remote invocation that might hang or be sluggish (long
timeout) it can drag the server down.
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2:25 a.m.
eval is only slower because it does not allow for indexing of data.
I don't believe your use case, which looks at nested data structures,
would allow indexing of data either.
So you'll probably gain in performance from a hard coded java method.
Mark
On 22/07/2012 03:40, lhorton wrote:
do not scoff so quickly, WL. eval() can be a big performance kill,
since
eval() condition is always executed during rule evaluation. For example,
if the eval is on a remote invocation that might hang or be sluggish (long
timeout) it can drag the server down.
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7 comments
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lhorton -
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Wolfgang Laun