[Gecode] Discarding propagators

[Christian Schulte]

Hi,

the problem is to call the propagate method directly: this is not possible!
The only interaction that is allowed for a propagator is creation!

What is not entirely clear to me why do you want to have temporay
propagators. As far as I understand, you are just using some propagation
method, that's it. Why not use a method that can be used without creating a
propagator first?

Christian

--
Christian Schulte, http://www.imit.kth.se/~schulte/ 

-----Original Message-----
From: gecode-bounces at ps.uni-sb.de [mailto:gecode-bounces at ps.uni-sb.de] On
Behalf Of Gustavo Gutierrez
Sent: Friday, March 18, 2005 11:00 PM
To: gecode at ps.uni-sb.de
Subject: [Gecode] Discarding propagators


Hi all,

Few weeks ago i posted a message with subject "design question". There, i
was trying to implement a propagator that uses other propagators to verify
some kind of consistency and then decide to prune or not domain values. That
is, the user-imposed propagator calls auxiliar propagators, and using the
outcome of such propagators, takes certain actions.

In order to do that without fall in space failures i use a copy of variables
and create a new propagator, then call the propagate method directly. This
new propagator needs to be disabled after the consistency proof (i.e. it
will not exist as long as ordinary propagators imposed by user). In order to
"simulate" propagator disabling i added a new method that contains a flag.
When the flag becomes true the propagate method returns ES_SUBSUMMED. My
hope is that the auxiliar propagator will be removed (in a safe way) from
the propagation queue at some time after this.

I was able of implementing the "main" propagator following this approach. My
problem is that it works fine in some examples, but for others it raises a
segfault. Very likely, I have a misassumption regarding the role and
functioning of the propagation queue. I would apprecciate any comments
and/or suggestions on this issue.

Thanks in advance,

Gustavo Gutierrez _______________________________________________
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