[Dune] Iterators with Partition

[Christian Engwer]

On Sun, Nov 14, 2010 at 03:27:19PM +0100, Jö Fahlke wrote:
> If I iterator over the range [gv.begin<0, Dune::Overlap_Partition>(),
> gv.begin<0, Dune::Overlap_Partition>()] which elements should I get:
> 
>  1. overlap elements only,
>  2. overlap + interior elements, or
>  3. any of the above (overlap + maybe interior elements)?
> 
> In UG I get 1. (empty range), in ALU3D I get 2. (interior elements only, I
> guess).  For Ghost_Partition, I seem to get only ghost elements in both cases.

I don't recall exactly, where the definition can be found (it should
be noted at least in the doxygen docs), but we discussed this issue
about a year ago...

- usually you iterate a growing set of entities,
  e.g. Overlap_Partition include all entities of
  overlap,border,interior.
- the main exception is ghost, where we iterate only over the ghost
  partition. Note that otherwise the Ghost_Partition iterator whouldn't
  be necessary, at this is already covered by the All-Iterator.

The naming is somewhat misleading, we already discussed the
possibility to compose arbirary iterators, using boolean operations.

Ciao
Christian