[vtk-developers] Wrapping enum types

[David Gobbi]

Hi All,

The enum support for the wrappers is done (pending merge).  The caveat
that I mentioned in my previous email no longer applies, i.e. with this new
patch _all_ enum types are wrapped, whether they are in the global
namespace, in a class namespace, or in any other namespace (except for
nested namespaces, which aren't supported by the wrappers yet).

This change isn't going to have much impact on the VTK core, because
most VTK class methods simply take "int" parameters instead of requiring
the use of enums.  However, it will have a _big_ impact for the wrapping
of third-party VTK classes which tend to use enum parameters quite often.
(In fact the change was motivated by the need to wrap some of my own
external classes).

Enum parameter support is only provided for the python wrappers, not for
Java or Tcl.

 - David


On Mon, Nov 17, 2014 at 7:04 AM, David Gobbi <david.gobbi at gmail.com> wrote:

> Hi All,
>
> I have a patch in gerrit that modifies the python wrappers so that enum
> types are wrapped.  This means that method parameters can be enum
> types, something that wasn't possible for wrapped methods before.
> http://review.source.kitware.com/#/c/17993
>
> E.g.:
>
> class vtkSomeObject
> {
> public:
>   enum ColorEnum { Red, Blue };
>   void SetColor(enum ColorEnum);
> };
>
> Each enum type is wrapped as a unique python type subclassed from
> python's "int" type.  So an enum can be used wherever an int can be
> used, but methods that take an enum will raise a TypeError unless
> given a value of the correct enum type.
>
> One caveat is that this only works if the method and the enum type are
> members of the same class.  Sometime later I'll generalize it so that a
> method can use an enum defined in a different class, but method & enum
> in the same class seems to be the most common use case.
>
> Cheers,
>
>   - David
>
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