[Dune-devel] Are IdSets persistent?

[Christian Engwer]

Hi Carstenm

On Tue, Apr 24, 2018 at 04:10:54PM +0200, Carsten Gräser wrote:
> Dear fellow developers,
> I recently stumbled upon the question if
> the IdSets obtained by grid.globalIdSet()
> and grid.localIdSet() are persistent?
> 
> To be more precise: Is it guaranteed that
> I can store a pointer for the obtained
> const-references and reuse it after grid
> modification?

as far as I always understood the interface, these objects are not
guaranteed to be valid until end of time. The persistence discussion
was only about the values. Still all examples used the IdSet also
after modification.

Christian

> 
> Looking at the code it seems that this is fact
> true, even for the grid implementations (at least
> in dune-grid and dune-alugrid) that create IdSets
> on demand. However, I'm unclear if this is
> guaranteed.
> 
> As far as I can see, the interface documentation
> does not comment on this question and I'm not aware
> of any discussion on this, but maybe I'm just
> forgetful or blind.
> 
> Best,
> Carsten
> 
> 
>