dolfin team mailing list archive

[Johan Hake <hake@xxxxxxxxx>]

On Wednesday 03 December 2008 15:43:43 Anders Logg wrote:
> On Wed, Dec 03, 2008 at 03:08:32PM +0100, Anders Logg wrote:
> > On Wed, Dec 03, 2008 at 02:57:09PM +0100, Johan Hake wrote:
> > > On Wednesday 03 December 2008 13:54:47 DOLFIN wrote:
> > > > One or more new changesets pushed to the primary dolfin repository.
> > > > A short summary of the last three changesets is included below.
> > > >
> > > > changeset:   5221:0e4bbb39f032405bcc4abfab501af49f6beb7b0b
> > > > tag:         tip
> > > > user:        Anders Logg <logg@xxxxxxxxx>
> > > > date:        Wed Dec 03 13:54:05 2008 +0100
> > > > files:       demo/pde/poisson/python/demo.py dolfin/swig/directors.i
> > > > dolfin/swig/dolfin_mesh_pre.i description:
> > > > Typemap fixes for SubDomain::inside(), seems to work now.
> > >
> > > Nice work!
> > >
> > > I suppose you are aware that the director typemap only kicks in for
> > > Function and SubDomain as these are the only director classes that
> > > includes a double* x, in one of their signatures. If other director
> > > classes in a possible future implements that signature, will trigger
> > > the typemap and that class need to implement geometric_dimension(). It
> > > is a nice way to solve the dimension problem of the numpy array, we
> > > just need to be aware of possible fragile side effects.
> >
> > Yes, that was the main point, to have a common typemap for both.
> >
> > > I introduced the class specific typemap with Function in mind, which
> > > you now have generalized to work for any "double* x" used in directors.
> > > We could hypotethize that this could be done for more "double*"
> > > typemaps too.
> > >
> > > Most of them are now implemented as a very fragile and greedy numpy
> > > typemap that kicks in every where a "double *" is expected. This
> > > typemap depends on the user passing the right dimension on the array to
> > > the function. This is inherited from the cpp interface where you have
> > > natural relationship to size of arrays. But I think that it does not
> > > scale to python.
> > >
> > > Optimally we should use a dimension check for each double * typemap
> > > that expect a numpy array, where the size of the numpy array is defined
> > > from the contex the type map is applied in. E.g. a type map for the
> > > Vector.set(), could check the size of the array agains the size of the
> > > Vector. The problem with this is to make a specific typemap that we
> > > know only kicks in for a particular class.
> >
> > I know too little SWIG to have an opinion on this.
> >
> > > To facilitate this we could change the parameter name in the
> > > Vector.set(double* value) to Vector.set(double* vecvalue) and to add
> > > the typemap:
> > > (pseudo code)
> > > %typemap(in) double* vecvalues {
> > >   {
> > >     Check input is numpy array.
> > >     // This is safe as long as only Vectors implement "double*
> > > vecvalues" Check dimension of numpy array agains self->size()
> > >     Assign the input statement.
> > >   }
> > > }
> >
> > But I'd like to avoid this (choosing special names for the arguments
> > in C++ just to please SWIG).
> >
> > > We should also %ignore alot of low level cpp only functions from the
> > > especially the la interface. Removing alot of the fragile double*
> > > typemaps that now kicks in everywhere.
> >
> > Agree!
> >
> > I'm about to get started on renaming dolfin.dolfin --> dolfin.cpp. Let's
> > see how it goes.
>
> Didn't go well. I don't know enough about the build system to make
> this work.
>
> Can you take a look?

Yes. I do it to night.

Johan