dolfin team mailing list archive

[Johan Hake <hake@xxxxxxxxx>]

On Monday 07 September 2009 10:53:24 Garth N. Wells wrote:
> Garth N. Wells wrote:
> > Ola Skavhaug wrote:
> >> On Wed, Aug 19, 2009 at 10:14 PM, <kent-and@xxxxxxxxx> wrote:
> >>>> I didn't realise until recently that storage in std::vector is
> >>>> guaranteed by the C++ standard to be contiguous (versus only being
> >>>> contiguous in all known implementations). Using this, I think that we
> >>>> can have safer and cleaner code by using more std::vector in the
> >>>> linear algebra interface. For example, we could have
> >>>>
> >>>>    GenericVector::get(std::vector<double>& );
> >>>>    GenericVector::set(const std::vector<double>& );
> >>>>
> >>>> instead of
> >>>>
> >>>>    GenericVector::get(double* x);
> >>>>    GenericVector::set(const double* x);
> >>>>
> >>>> For backends that want a pointer to an array, we can pass &x[0]. Any
> >>>> opinions?
> >>>
> >>> Is the use of &x[0] safe ? Will it change if the vector is resized ?
> >>> This is maybe
> >>> nothing to worry about ?
> >>
> >> Sure, this is something to worry about, and there will be no magic here
> >> :) However, it will enable us to make range checks and issue error
> >> messages more easily.
> >
> > We wouldn't let any objects store a pointer to &x[0]. Just as we don't
> > now - it's just data in, data out. On top of the points made by Ola, it
> > will also reduce the likelihood of memory leaks. We can also eliminate
> > some redundant copying of std::vectors into arrays and back.
> >
> > Garth
> 
> I've created Blueprint for this:
> 
>     https://blueprints.launchpad.net/dolfin/+spec/stl-vectors-la
> 
> and set the status to 'Discussion'.

I tried to make a comment on this. I put it at the "Whiteboard". Not sure 
where to put it else?

Johan

> Garth
> 
> >> Ola
> >>
> >>> Kent
> >>>
> >>>> Garth
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