JESS: A problem with accumulate
Hi,I have a serious problem with accumulate, I wanted to use it on some shadow facts, but I noticed that I can't have more than one contained CE.I would need to use a Time-varying method (OBJECT) and a test-CE in the matching part of the Accumulate... Something like (modifed from the manual): ?c - (accumulate (bind ?list (new java.util.ArrayList)) (?list add ?o) ?list (employee (OBJECT ?o))(test (?o xyzMethod arg1)) ; - that can't work if I understand correctly :( = (printout t (?c toString) crlf)) This causes me some serious trouble, so I'll hope there is a way to deal with it. Thanks again ! _ Soyez parmi les premiers à essayer Windows Live Mail. http://ideas.live.com/programpage.aspx?versionId=5d21c51a-b161-4314-9b0e-4911fb2b2e6d
Re: JESS: A problem with accumulate
On Dec 2, 2006, at 2:28 AM, Skeptic 2000 wrote: Hi, I have a serious problem with accumulate, I wanted to use it on some shadow facts, but I noticed that I can't have more than one contained CE. Yes, that's a limitation of the current implementation; it should be lifted for Jess 7.1. Something like (modifed from the manual): ?c - (accumulate (bind ?list (new java.util.ArrayList)) (?list add ?o) ?list (employee (OBJECT ?o)) (test (?o xyzMethod arg1)) ; - that can't work if I understand correctly :( = (printout t (?c toString) crlf)) In this case, there would be no problem with just adding the call to xyzMethod to the employee CE directly -- i.e., (employee (OBJECT ?o:(?o xyzMethod arg1))) --- Ernest Friedman-Hill Advanced Software Research Phone: (925) 294-2154 Sandia National LabsFAX: (925) 294-2234 PO Box 969, MS 9012 [EMAIL PROTECTED] Livermore, CA 94550 http://www.jessrules.com To unsubscribe, send the words 'unsubscribe jess-users [EMAIL PROTECTED]' in the BODY of a message to [EMAIL PROTECTED], NOT to the list (use your own address!) List problems? Notify [EMAIL PROTECTED]
JESS: agenda change in Jess 7.0 and custom Strategies
I've found that the method below behaves differently in Jess 7.0b7 and
the formal v7.0 release. In the formal release, the Activations
provided by the Iterator in 2 successive calls to Rete.listActivations()
are different objects, even if nothing has happened between the calls.
The change has ramifications for those with custom Strategy
implementations. In our case, we scan the agenda for a particular
Activation to favor before calling run(), and then our Strategy's
compare() method tests its arguments for that object with the == operator.
We can, with some impact on performance (presumably negligible on short
agendas), use the Activation.equals() method instead of the ==
operator. But I wanted to ask about the intent of the change, and
whether it's likely to be permanent. I hadn't seen (but could have
simply missed) mention of it in the notes since beta 7. Thanks very much,
Jonathan
public void dumpAgenda(String label) {
Map actMap = new HashMap();
Iterator it = listActivations(); // get the agenda and
store Activations
for (int i = 0; it.hasNext(); ++i) {
Activation a = (Activation) it.next();
actMap.put(new Integer(a.hashCode()), a);
}
it = listActivations(); // get the agenda again; no
intervening activity
for (int i = 0; it.hasNext(); ++i) {
Activation a = (Activation) it.next();
Activation aa = (Activation) actMap.get(new
Integer(a.hashCode()));
System.out.println(agenda a[+i+]+
(aa == null ? not : )+ in map,+ // aa !=
null in both v7.0b7 and 7.0
(a == aa ? : not)+ same obj); // aa == a
only in v7.0b7
}
}
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Re: JESS: agenda change in Jess 7.0 and custom Strategies
A good technical question!
The method listActivations() is not used internally by Jess; it's
just provided for use by tools of various kinds. It's a fairly
expensive method because it makes a copy of the whole agenda, and
iterating over this copy does a full sort. The copy is necessary; the
process of iterating over all the activations is destructive. They're
not kept in sorted order -- they're pulled out just in time. Anyway
concern over using == vs equals() may be misplaced -- this is a small
difference compared to the overall expense of copying the whole
agenda. This much has always been true.
What's changed in 7.0 is that an Activation object can't be part of
more than one agenda at a time, because the Activation knows where
in the agenda it lies. In older versions, the same Activation objects
would live in the copied agenda as in the original; now copies are
made of all the Activations, too. This new property of Activation
objects is an optimization; it makes the process of removing
activations from the agenda before firing them (due to a retraction,
for example) much more efficient.
I thought of this as an internal implementation detail and so didn't
document it, but the change is permanent.
On Dec 2, 2006, at 8:07 PM, Jonathan Sewall wrote:
I've found that the method below behaves differently in Jess 7.0b7
and the formal v7.0 release. In the formal release, the
Activations provided by the Iterator in 2 successive calls to
Rete.listActivations() are different objects, even if nothing has
happened between the calls. The change has ramifications for those
with custom Strategy implementations. In our case, we scan the
agenda for a particular Activation to favor before calling run(),
and then our Strategy's compare() method tests its arguments for
that object with the == operator.
We can, with some impact on performance (presumably negligible on
short agendas), use the Activation.equals() method instead of the
== operator. But I wanted to ask about the intent of the change,
and whether it's likely to be permanent. I hadn't seen (but could
have simply missed) mention of it in the notes since beta 7.
Thanks very much,
Jonathan
public void dumpAgenda(String label) {
Map actMap = new HashMap();
Iterator it = listActivations(); // get the agenda and
store Activations
for (int i = 0; it.hasNext(); ++i) {
Activation a = (Activation) it.next();
actMap.put(new Integer(a.hashCode()), a);
}
it = listActivations(); // get the agenda again; no
intervening activity
for (int i = 0; it.hasNext(); ++i) {
Activation a = (Activation) it.next();
Activation aa = (Activation) actMap.get(new Integer
(a.hashCode()));
System.out.println(agenda a[+i+]+
(aa == null ? not : )+ in map,+ // aa !
= null in both v7.0b7 and 7.0
(a == aa ? : not)+ same obj); // aa
== a only in v7.0b7
}
}
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[EMAIL PROTECTED]'
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[EMAIL PROTECTED]
-
Ernest Friedman-Hill
Advanced Software Research Phone: (925) 294-2154
Sandia National LabsFAX: (925) 294-2234
PO Box 969, MS 9012 [EMAIL PROTECTED]
Livermore, CA 94550 http://www.jessrules.com
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