Yes, that can be done. There is even a virtual base class for it (so a type for all engines). It is Gecode::Search::Engine.
Cheers Christian -- Christian Schulte, Professor of Computer Science, KTH, www.ict.kth.se/~cschulte/ -----Original Message----- From: Kish Shen [mailto:kiss...@cisco.com] Sent: Wednesday, August 21, 2013 6:53 AM To: cschu...@kth.se Cc: users@gecode.org Subject: Re: [gecode-users] Adding restart-based search to ECLiPSe's interface to Gecode Hi Christian, Thanks for your reply! On 20/08/2013 20:51, Christian Schulte wrote: > Hi Kish, > > Sorry for the delay, I was on holidays and I am still catching up. > > You are basically on your own. The stuff in the Search namespace is > not documented in MPG for a reason ;-) I don't mind changing the existing code more extensively, but I think I probably would need to have a pointer to a 'search engine' thingy (currently I have a class -- GecodeSearch for this, sengine is not visible outside the class), which I can set to the appropriate search or meta- search engine, and for which I can call a next() function to get the next solution. Can this be done? > Having said that, the stuff you are doing might work and I have an > idea where the problem is: the meta engine deletes the engine that you > pass to it (so sengine0 in your example). That means you are not > allowed to delete it yourself in your code. But as said, just an idea. I actually do not delete sengine0 already, i.e. in ~GecodeSearch, I only delete sengine. This was because deleting segine0 crashed. Cheers, Kish > Cheers > Christian > > -- > Christian Schulte, www.ict.kth.se/~cschulte/ > >> -----Original Message----- >> From: users-boun...@gecode.org [mailto:users-boun...@gecode.org] On >> Behalf Of Kish Shen >> Sent: Friday, August 16, 2013 10:17 PM >> To: users@gecode.org >> Subject: [gecode-users] Adding restart-based search to ECLiPSe's >> interface > to >> Gecode >> >> Hi, >> >> I am still trying to figure out how to add restart based search to > ECLiPSe's >> interface to Gecode. I tried modifying my existing code (which does >> not > support >> restart-based search), and managed to get a restarted based bab >> search to return the optimal answer, but the code then crashes, >> probably because I > am >> not doing things correctly. >> >> If someone can point me in the right direction, I would be very grateful. > I sent a >> message about this about 2 weeks ago to this mailing list, but >> perhaps I > did not >> give the correct information to get any help, so I will try again. >> >> An outline of what I am doing now: >> >> The user defines the problem to be solved in ECLiPSe, and the >> interface > maps >> this to Gecode. At the Gecode level, the problem is represented in > GecodeSpace, >> which is derived from Gecode::MinimizeSpace >> >> Searching can be done with a Gecode search engine, or it can be done >> at > the >> ECLiPSe level (in which case search engines are not used). >> >> To do the search with a search engine, I have a GecodeSearch class, >> which > has a >> Search::Engine* sengine, which is then dynamically assigned with the > problem >> and search engine type when the user specify that a search is to be >> done > by >> Gecode with a particular search method (like bab), e.g. >> >> solver->vCost = <Cost variable> >> sengine = Search::bab(solver, option) >> >> where solver is a GecodeSpace*, and vCost is the cost variable (for >> MinimizeSpace). >> >> The MPG describes the search engine classes such as BAB, which I >> don't use directly. I think the reason is that I want to be able to >> assign different > types of >> search engines to sengine, as the search type is only known at >> run-time, > and in >> fact the user can call search as often as they like on the same problem. >> >> My problem is that I cannot extend this current scheme to work with > restart- >> based search. What I tried was to use Search::rbs, which is also of >> class > Engine*, >> and so can be assigned to sengine, but this crashed after returning >> the > solution: >> >> sengine0 = Search::bab(solver, option); sengine = Search::rbs(solver, >> metastop, sengine0, metaoption); >> >> I needed to use an extra Engine* sengine0, because using the same >> engine > in >> bab and rbs crashed immediately. >> >> The crash seems to happen when the rbs engine is destroyed, and it >> looks > like it >> is related to using 2 search engines. >> >> Is rbs supposed to be used by the user? I found it by looking for rbs >> in > the >> documentation, but I noticed that although it is listed, it doesn't >> seem > to have >> any description associated with it. >> >> Can I use Engine* in this way if I want to use restart-based search, >> or do > I need >> to use something else (i.e. not a Engine*)? >> >> Thanks in advance for any help! >> >> Cheers, >> >> Kish >> >> _______________________________________________ >> Gecode users mailing list >> users@gecode.org >> https://www.gecode.org/mailman/listinfo/gecode-users > _______________________________________________ Gecode users mailing list users@gecode.org https://www.gecode.org/mailman/listinfo/gecode-users
