dolfin team mailing list archive

[Johan Hake <johan.hake@xxxxxxxxx>]

On Monday August 16 2010 10:07:41 Anders Logg wrote:
> On Mon, Aug 16, 2010 at 09:57:26AM -0700, Johan Hake wrote:
> > On Monday August 16 2010 05:51:24 noreply@xxxxxxxxxxxxx wrote:
> > > ------------------------------------------------------------
> > > revno: 4986
> > > committer: Anders Logg <logg@xxxxxxxxx>
> > > branch nick: dolfin-dev
> > > timestamp: Mon 2010-08-16 14:48:44 +0200
> > > 
> > > message:
> > >   Implement named MeshFunctions in Python. Might be a better way (using
> > > 
> > > SWIG magic).
> > 
> > I think it is fine. The only reason we would like to wrap it using SWIG
> > would be to preserve the types. So one could check if a passed
> > MeshFunction is for example a VertexFunction. But I think we should not
> > encourage that and instead use dim.
> 
> ok.
> 
> > When I looked at the Python implementation I wonder if we should
> > harmonize the data type setting with NumPy. Instead of 'int' pass either
> > int or 'i', and so on.
> > 
> > If you agree, do you know of any other place where we could do such a
> > harmonizing?
> 
> Isn't the problem that with "uint" we get the expected type (that
> matches dolfin::uint in C++). Last time I checked, the NumPy list of
> int types is a jungle of different options.

Yes, but we have setled in the NumPy typemaps on the correct one. It is to use 
"I" or unit32 for unsigned int. This will not be any problem eitherway as 
these types are just used to instantiate the correct MeshFunctionFoo. in the 
same "switch" statement we have now.

> > I also think it is better to implement the named MeshFunctions as
> > inheriting from MeshFunction, instead of just beeing functions that
> > returns. I can fix this.
> 
> I tried but it didn't work (the constructors were not called) but I'm
> sure you know how to fix it. :-)

Just use __new__:

  class VertexFunction(MeshFunction):
    "Create MeshFunction of topological dimension 0 on given mesh."
    def __new__(self, value_type, mesh):
        return MeshFunction.__new__(self, value_type, mesh, 0)


Johan