dolfin team mailing list archive

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

On Fri, Nov 2, 2012 at 6:29 PM, Anders Logg <logg@xxxxxxxxx> wrote:
> The dolfin-csg branch (and the dolfin-plot) branch are getting ready
> for merge.
>

Nice.

> Benjamin and Johannes have worked on adding functionality
> for generating meshes from geometries described by constructive solid
> geometry (CSG):
>
>   geometry = circle*triangle + square - polygon
>   mesh = Mesh(geometry)
>
> Before merging, what are the opinions of where to put the primitives,
> in which namespace? Normally, we put everything into namespace dolfin,
> but some of the new primitives may clash with existing classes for
> mesh generation (UnitSquare etc).
>
> To keep things simple, I would like to put everything in namespace
> dolfin, so the CSG geometries become a natural part of the FEniCS
> interface, not something one has to import from a separate namespace
> (dolfin::csg).
>
> The new primitives are
>
>   Circle     (2D)
>   Ellipse    (2D)
>   Rectangle  (2D)
>   Polygon    (2D)
>
>   Sphere     (3D)
>   Box        (3D)
>   Cone       (3D)
>   Cylinder   (3D)
>

No polyhedron? I added a CGAL-based mesh generation interface a while
back that supported polyhedra, so I imagine that some of the necessary
code for creating a polyhedron is already there.

> Existing mesh classes that the above may clash with are
>
>   Interval
>   Rectangle
>   UnitCircle
>   UnitCube
>   UnitInterval
>   UnitSphere        --> remove because it has bad quality mesh?
>   UnitSquare
>   UnitTetrahedron
>   UnitTriangle
>
> These are mostly prefixed by "Unit" so that may take care of some of
> the ambiguities.

The prefix may technically remove the ambiguity, but a practical
ambiguity between 'shapes' and 'meshes' persists,

>One could also argue that we should rename to
> UnitSquareMesh etc, but it would break compatibility.
>
> One option could be to rename mesh classes to UnitSquareMesh,
> UnitCubeMesh, and keep deprecated (sub)classes UnitSquare, UnitCube
> indefinitely to keep backwards compatibility.
>

No point in renaming if the deprecated names are to be kept indefinitely.

> In summary, I would like to add the new classes to namespace dolfin
> but I'm looking for opinions on how to best handle naming conflicts.
>

I'm always in favour of a consistent, meaningful interface over a
sub-optimal interface for the purpose of backward compatibility.

Garth

> --
> Anders
>
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