[gecode-users] Gecode/J: What is Space abstract?

[Mikael Zayenz Lagerkvist]

On 11/7/07, Malcolm Ryan <malcolmr at cse.unsw.edu.au> wrote:
> Wouldn't it be a good idea to add an abstract copy() function to Space
> () then, enforcing this requirement, rather than just assuming the
> copy constructor will be there? This is what you do on GecodeVar
> after all.

I don't know of a way to require statically that a constructor with a
certain signature should be available in a class. However, if the copy
function is called and there is no constructor with the right
signature, an exception will be thrown alerting you to the fact.

An abstract function in Space would only be enforced in direct
inheritance from Space. If you had your own MySpace, and then made a
class MySpecialSpace inheriting from MySpace, there would be no error
if that function was left out.


On the C++-side of Gecode, each Space must implement both a virtual
function copy, as well as a copy constructor. The virtual
copy-function is used as a polymorphic trampoline for accessing the
right copy-constructor. Since Gecode/J is geared mainly towards
teaching, we have tried to simplify the set-up for a normal model as
far as possible. Using Java reflection, we could dispense with this
function and write a generic one in the Space-class.

Cheers,
Mikael

-- 
Mikael Zayenz Lagerkvist, http://www.ict.kth.se/~zayenz/