Hi all,
I am trying to re-engineer some piece of code we wrote for enabling Large
Neighborhood Search within Gecode and I am facing the problem (which has also
some general sense) of passing specific parameters (or options objects) to an
engine that has to be managed through the Script<Space>::run<…>() execution
method.
Since I would like to contribute the LNS code to the Gecode community, before
undertaking modifications in my Gecode working copy I would like to agree it
with Gecode maintainers since it will have a (I would say minor) impact on the
framework.
Other solutions to the problem from more "knowledgeable users" are, of course,
welcome. :-)
Coming to the problem, in detail, the specific option object that is passed to
the run method is dispatched in the Script::run function and a brand new
Search::Option object is sent to the actual engine. Unfortunately this means
that the specific engine could not have access to its specific options and I
found it a general limitation.
Of course it is possible to overcome this limits with workarounds, but they
will somehow break the general framework philosophy.
To be generic enough, my proposal is to add a "Gecode::Options* parameters"
attribute to the Search::Options class in order to allow sending this specific
information to the engine. This variable should be set in the
Script::run(Options, Script) dispatching, e.g., by invoking some "parameters()"
function on the "Gecode::Options& option" object passed to run.
Just sketching the "pseudo diff" of the tentative modification it will be
something like this:
At search.hh around line 210 add the line
Gecode::Options* parameters;
At script.hpp around line 300 add the line
so.parameters = o.parameters();
And, at options.hpp around line 148 add the lines
inline
Options* parameters() {
return NULL; // for default no specific option is passed to the engine
}
This way, the engine has access to parameters and it can cast it to the
opportune parameter class.
Thanks in advance for comments and/or suggestions.
All the best,
Luca
_______________________________________________
Gecode users mailing list
[email protected]
https://www.gecode.org/mailman/listinfo/gecode-users
