[Dune] Returning Geometries As Objects

[Martin Nolte]

Dear all,

as decided on the last developer meeting in Münster, I will now start to 
change all grid implementations to return the geometry by object. The main 
reason for this change is (as far as I remember) a negative performance impact 
on meta grids. But when experimenting I also noted a minor performance gain 
for SPGrid itself.

Note: This change will only have an impact on user code, a geometry reference 
is passed beyond the scope it was obtained in, e.g.,

const Geometry *pgeo = 0;
{
   const Geometry &geo = entity.geometry();
   pgeo = &geo;
}

Therefore, this change might have some impact on the higher discretization 
modules, such as dune-fem, dune-fufem, or dune-pdelab.

In order to make this transition as smooth as possible, I just created a 
branch in dune-grid. All changes will be made here, and it will not be merged 
back without previous discussion. I hope we won't run into merging trouble, 
though.

Best,

Martin

-- 
Martin Nolte <nolte at mathematik.uni-freiburg.de>

Universität Freiburg                                   phone: +49-761-203-5630
Abteilung für angewandte Mathematik                    fax:   +49-761-203-5632
Hermann-Herder-Straße 10
79104 Freiburg, Germany