dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Sun, Feb 07, 2010 at 10:58:44PM +0000, Garth N. Wells wrote:
>
>
> Anders Logg wrote:
> > This looks a like a non-optimal solution. Are you returning the mesh
> > by value? That will lead to creation of a temporary and copying of the
> > entire refined mesh.
> >
>
> So they used say ;). Apparently modern compilers are all clever enough
> not to.
>
> Garth

Is that really so? Do you have any good references that explain this
in detail? This could potentially lead to many changes in DOLFIN where
we could return by value rather than by reference with the prime
example being

  A = assemble(a);

But does it really handle non-copying of a wrapped PETSc data structure?

--
Anders


> > What if we have
> >
> >   FooRefinement::refine(old_mesh, new_mesh)
> >
> > or similar?
> >
> >> ------------------------------------------------------------
> >> revno: 4461
> >> committer: Garth N. Wells <gnw20@xxxxxxxxx>
> >> branch nick: dolfin-nompi
> >> timestamp: Sun 2010-02-07 21:53:42 +0000
> >> message:
> >>   Work on mesh refinement interface.
> >>
> >>   Do not overwrite old mesh inside refinement functions belonging to static classes. Need to keep old mesh to peform update in adapative methods, so previously the mesh had to be copied before calling refine(...).
> >> modified:
> >

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