[Dune] Returning Geometries As Objects

[Robert Kloefkorn]

Hi all,

 > I think we can go with Andreas suggestion: If nobody steps forward on
 > a potential performance loss in his current code, we don't really
 > need a transition phase on this. The code will compile as it did
 > before (except for the potentially dangling references that we have
 > to cope with anyway).

 > From the discussion (or rather from the silence) I conclude the
 > following:
 > (a) We state in the documentation that the returned geometry object 
 > has to be valid until the next grid modification.
 > (b) We let the constructor of Dune::Geometry give a deprecation
 > warning, if StoreGeometryReference::v is true, thus issueing a
 > warning to the user.

I agree with the suggestions of Martins and Andreas. A warning for 
possibly dangling references will be sufficient for a more or less short 
transition phase.

Best

R

PS:

@Oli:

 > I know speed matters a great deal to your group, but I don't think you
 > guys are representative for the greater Dune community.

Fortunately, we don't rely on what you think.