[Dune] Capability hasLevelIterator? (was: Capability hasLeafIterator?)

[Markus Blatt]

Hi,

On Wed, Oct 18, 2006 at 10:23:19AM +0200, Oliver Sander wrote:
> I think making level iterators optional is a point worth considering.
> Already it seems to me (am I right?) that one grid implementation
> doesn't implement them.
> 

speaking for Stuttgart again, I would like to continue the discussion
whether to introduce a new Capability hasLevelIterator.

We think that (at least for the current code) with exception of
implementation of geometric multigrid methods the LevelIterator is
not mandatory. There are already grids (e. g. NetworkGrid) under the Dune
Interface that cannot support LevelIterators in an efficient (and
complete) way and there might be more implementations with this inability

Introducing the hasLevelIterator capability would allow even those
implementations under the Dune Interface without breaking the Grid
tests.

Therefore Stuttgart votes for introducing te hasLevelIterator
capability.

What is the opinion in Freiburg concerning this issue?

Cheers,

Markus Blatt