ffc team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Wed, Dec 03, 2008 at 05:04:37PM +0100, Martin Sandve Alnæs wrote:
> 2008/12/3 Garth N. Wells <gnw20@xxxxxxxxx>:
> >
> >
> > Martin Sandve Alnæs wrote:
> >>
> >> There is a signature:
> >>
> >>  // Create form on given function space(s) with given coefficient(s)
> >> (shared data)
> >>  PoissonLinearForm(std::tr1::shared_ptr<const dolfin::FunctionSpace>
> >> V0, dolfin::Function& w0) : dolfin::Form(), f(*this)
> >>
> >> but no signature where both the function spaces and functions are
> >> shared pointers. For an application with full use of shared pointers,
> >> we need that.
> >>
> >
> > I don't think that it's required. I brought this point up a while ago,
> >
> >  http://www.fenics.org/pipermail/ffc-dev/2008-November/001923.html
> 
> Quoting this:
> """
> On Thu, Nov 06, 2008 at 08:14:47PM +0000, Garth N. Wells wrote:
> > For the 'shared' versions, shouldn't the coefficients also be shared
> > pointers?
> 
> It's not necessary since these arguments will not be stored as
> data. They will just be assigned to the coefficients.
> """
> 
> That's just plain wrong. Through Coefficient::attach, the Form will
> store shared pointers to them with NoDeleters, and these pointers
> won't share the reference count of an eventual shared pointer I
> have in my application.

Yes, that seems to be wrong.

Do you need shared_ptr only in the constructors or do you also want
shared_ptr for the assignment operator?

Is it possible to reuse the DOLFIN-wrappers from dolfinformat.py in
FFC? It would be practical if we could reuse the same code since it's
a bit messy to generate with all the different combinations of
constructors with and without shared_ptr etc. It would also increase
the chances for generating compatible code.

Perhaps it can be placed in UFC, say under src/utils/python/dolfin?
It could be a single function that gets the form name(s) as input, the
list of coefficient names etc so it would be independent of the
form-compiler.

-- 
Anders

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