Gecode/R 0.9.0
Gecode/R 0.9.0 has been released. It contains all the functionality that has been planned for 1.0.0.
Details are found in the announcement. It adds a bit of sugar, fixes some bugs and changes the way constraints work. The latter results in that one can place constraints such as
(set1.size + set2.size).must > int.abs - 3
The RDoc documentation is now also much nicer.
I'm not so sure that the amount of work that went into redoing the way constraints work (about one and a half week) was really worth it from the user's point of view. I suspect that I did it more to get rid of the rather ad-hoc "composite constraints". They should have been replaced much sooner (preferably around 0.5.0) to avoid the overhead.
Changes:
- Variables that should be accessible from outside the model can now be created by calling "<variable_name>_is_a <variable>" where "<variable_name>" is the desired name of the variable and "<variable>" is the variable (e.g. "int_var(17)").
- Gecode.solve, Gecode.maximize and Gecode.minimize can now be used to solve a problem without first having to explicitly create a class for the model.
- An exception (Gecode::NoSolutionError) is now thrown if a solution can not be found when using Model#solve!, Model#minimize!, Model#maximize! and Model#optimize! (rather than returning nil). This change breaks backwards compatibility. If you feel that this is a bad change then please tell the mailing list.
- The offset option to the distinct constraint is now given as "int_enum.must_be.distinct(:offset => offsets)" rather than the previous "int_enum.with_offsets(offsets).must_be.distinct".
- Complex combinations of several constraints such as "(set1.size + set2.size).must > int.abs - 3" can now be used. The underlying code has been changed quite a bit, but it should remain backwards compatible except for above mentioned exception. The change also brings about some changed terminology, which mostly aims to remove the concept of "composite constraints" and replace them with the more general "operands".
- [#21578] Fixed a bug that caused options given to the boolean "false" domain constraint to not be processed.
- [#21579] Fixed a bug that caused the integer enumeration equality constraint to not work at all (threw an exception).
- [#21580] Fixed a bug that caused ranges that use three dots to not be correctly interpreted by the negated integer domain constraint.
- [#21581] Fixed a bug that caused the abs constraint to prune away valid solutions in some cases.