dolfin team mailing list archive

[Johan Hake <hake@xxxxxxxxx>]

On Wednesday 04 March 2009 13:50:18 Anders Logg wrote:
> On Wed, Mar 04, 2009 at 01:39:10PM +0100, Johan Hake wrote:
> > On Wednesday 04 March 2009 13:34:17 Anders Logg wrote:
> > > On Wed, Mar 04, 2009 at 01:28:10PM +0100, Johan Hake wrote:
> > > > On Wednesday 04 March 2009 13:17:37 Garth N. Wells wrote:
> > > > > When running demo/mesh/intersection/demo.py, I get
> > > > >
> > > > >      Traceback (most recent call last):
> > > > >        File "demo.py", line 33, in <module>
> > > > >          cells = STLVectorUInt()
> > > > >      NameError: name 'STLVectorUInt' is not defined
> > > > >
> > > > > Any ideas?
> > > >
> > > > Should be fixed now
> > >
> > > How is the STL integration with Python lists? The optimal thing would
> > > be if one could write
> > >
> > >   cells = omega0.intersection(boundary, False)
> > >
> > > instead of
> > >
> > >   cells = STLVectorUInt()
> > >   omega0.intersection(boundary, cells, False)
> > >
> > > and cells would be a Python list.
> >
> > Agree on this.
> >
> > Should be doable with the right typemaps.
> >
> > I can fix it but not right now...
>
> ok, nice.
>
> > Is this the only place where we use STLVectorFoo?
>
> Yes, at least in the demos. It (std::vector) appears in quite a few
> places now in function calls in the C++ interface, but it's mostly
> invisible from Python. For example, the Assembler uses this but it's
> wrapped and handled from Python with standard Python lists or tuples.

Ok, I see that it is needed in assemble_system and VariationalProblem also use 
it. I think it would be doable to remove all these from the python interface, 
with a proper typemap.

I could e.g. add a typemap macro for all type Foo, that we want to be able to 
pass to the c++ as std::vector<Foo>, using any iterable from python, e.g., 
tuple, list and numpy arrays.

The output typemap of intersection detector will probably need some extra 
attention.

Johan

> > I feel that this type is a
> > bit too low level to be used in the python interface, and we should as
> > you suggest try to get rid of it.
>
> Yes, it's a bit ugly.