[gecode-users] access to Space during branching?
Christian Schulte
schulte at imit.kth.se
Mon Jun 5 12:46:09 CEST 2006
Of course you can do that! However: how do you know what are the views?
Views are very cheap (just a pointer) so there should be no need to put
anything globally into the space.
Christian
-----Original Message-----
From: Luis Quesada [mailto:luque at info.ucl.ac.be]
Sent: Monday, June 05, 2006 12:32 PM
To: Christian Schulte
Cc: 'gecode user list'
Subject: Re: [gecode-users] access to Space during branching?
Christian Schulte wrote:
>No, you always have to update views! If a propagator stores a view it
>must be updated. In the situation you describe it will be that the
>variable implementations to which the views stored in the space have
>already been updated (that is, a copy has been created). However, also
>the views in the propagators must be updated to point to the copied
>variable implementations.
>
>
>
OK, I see your point! However, do the propagators (in the particular
situation I am describing) need to store the views (taking into account
that the space is an argument (and that I can have access to the views
through the space))?
Luis
>Christian
>
>-----Original Message-----
>From: Luis Quesada [mailto:luque at info.ucl.ac.be]
>Sent: Monday, June 05, 2006 12:01 PM
>To: Christian Schulte
>Cc: 'gecode user list'
>Subject: Re: [gecode-users] access to Space during branching?
>
>
>Christian Schulte wrote:
>
>
>
>>Yes, you got it right. It has been really a mistake to not pass a
>>space
>>argument to branch: everything is constructed in such a way that one
>>never has to store a space anywhere: no Gecode data structure stores a
>>space, all is passed as arguments.
>>
>>
>>
>>
>>
>Thanks for your confirmation.
>
>In fact, this made me remember another question: suppose that in my
>program all the propagators are using the same views of the variables
>(i.e., there is only one view per variable) and theses views are updated
>in the constructor for cloning of the space. Is it correct to say that
>there is no need of updating these views in the constructor for cloning
>of the propagators (since these views are already updated in the
>constructor for cloning of the space)?
>
>Luis
>
>
>
--
Luis QUESADA
Catholic University of Louvain
Department of Computing Science and Engineering
Place Sainte Barbe, 2
B-1348 Louvain-la-Neuve, Belgium
Phone: (++32) (10) 47 90 13
Fax: (++32) (10) 45 03 45
Web: http://www.info.ucl.ac.be/~luque
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