dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Martin Sandve Alnæs wrote:
> 2008/8/23 Garth N. Wells <gnw20@xxxxxxxxx>:
> > Martin Sandve Alnæs wrote:
> > > 2008/8/23 Garth N. Wells <gnw20@xxxxxxxxx>:
> > > > Martin Sandve Alnæs wrote:
> > > > > Add an instantiation of Array<DirichletBC*> to the .i files beside
> > > > > ArrayFunctionPtr.
> > > > I added this.
> > > >
> > > > > An use cpp_DirichletBC.
> > > > I tried this is demo/pde/sym-dirichlet-bc/python/demo.py, but I get
> > > >
> > > > Traceback (most recent call last):
> > > >  File "demo.py", line 55, in <module>
> > > >   bc = cpp_DirichletBC(u0, mesh, boundary)
> > > > NameError: name 'cpp_DirichletBC' is not defined
> > > from dolfin.dolfin import cpp_DirichletBC
> > >
> > > Note that cpp_DirichletBC won't hold on to python referenced objects,
> > > so you need to keep some python references to your meshfunctions
> > > and vectors etc. to avoid garbage collection.
> > >
> > > > As you say, this is a problem with this
> > > > > "inheritance pattern".
> > > > Is there a way to 'up cast' Python objects. For example, DirichletBC is
> > > > derived from cpp_DirichletBC, so can I get a cast a DirichletBC object to
> > > > a
> > > > cpp_DirichletBC object?
> > > >
> > > > Garth
> > > The DirichletBC object is already a cpp_DirichletBC object, it obviously
> > > works fine for single objects, so the problem is in the vector typemap.
> > > Maybe you can create an empty ArrayDirichletBC() and add one item
> > > at a time to it?
> > >
> > > a = ArrayDirichletBC()
> > > for b in bcs:
> > >    a.push_back(b)
> > No luck. I've pushed some code, but it doesn't work. Try running
> >
> >  demo/pde/sym-dirichlet-bc/python/demo.py
> >
> > Garth
>
> I'll try it. But this should work, we do the exact same thing with
> functions in assemble.py.
>
>     _coefficients = ArrayFunctionPtr()
> ...
>             for c in form_data.coefficients:
>                 _coefficients.push_back(c.f)
>
> form_data is from ffc.jit, so c.f is a dolfin.Function, the kind that
> inherits ffc.Function as well as cpp_Function.

I included Array.h in assemble.cpp and that did the trick (I've since 
moved the #include to Assemble.h). I have no idea why this makes it work.

Garth


> --
> Martin