Re: [eclipse-clp-users] Data Passing from C++ to Eclipse

From: Joachim Schimpf (Independent Contractor) <jschimpf_at_...5...>
Date: Tue, 10 Jun 2008 10:55:36 +0100
Vivek Balaraman wrote:
> Joachim,
> Thanks for the information.
>  
> My response to the last part of your mail
> 
>  
> On 6/9/08, *Joachim Schimpf (Independent Contractor)* 
> <jschimpf@...5... <mailto:jschimpf@...5...>> wrote:
> 
> 
>     How are you going to compute several solutions?  Are they computed one
>     by one from scratch, or all in one go, or are alternative solutions
>     produced on backtracking, etc?
> 
>  
>  
> Our current code in eclipse calculates a solution, stores it in a store 
> and then calls fail causing it to backtrack and find other 
> solutions. Then either when all solutions or number of solutions > 50 
> used to send the solutions to the calling program one by one using the 
> write_exdr operations.
>  
> something like
>  
> calc_all_scenarios:-
>  
>  (
>  
>  calc_one_scenario ([Index, Solution]),
>  
>  store_put(Store, Index,Solution),
>  
>  Additionally also increment the count of solutions in a counter
>  
>  fail
>  
>  ;
>  
>  Lookup counter to get number of solutions
>  
> For all solutions, store_get(Store,I, Solution), write solution to queue
>  
> ).

Using the C/C++ interface, there is no need to use queues, you can read
the store contents directly by posting store_get/3 goals, i.e.

	EC_Ref solution;
	int index = ...;
	post_goal(term(EC_functor("store_get",3), "my_store_name", index, solution));
	EC_resume();



Another solution, which is possible with the C/C++ interface, is to have the
fail-loop in C++.  In that scenario, you would initially post calc_one_scenario/1
and resume.  When this succeeds and returns to C++, you have one solution and can 
process it in C++.  You then post a fail/0 and resume, and this will succeed with 
the next solution and return to C++, and so on.  No need to use stores.
An example is in doc/examples/eg_cc_fail_loop.cc


-- Joachim
Received on Tue Jun 10 2008 - 02:55:47 CEST

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