[PyQt] Construct QVariant from object of user type

[Arve Knudsen]

On 4/17/08, Arve Knudsen <arve.knudsen at gmail.com> wrote:
> On 4/17/08, Matt Newell <newellm at blur.com> wrote:
>  > On Wednesday 16 April 2008 14:18:26 Arve Knudsen wrote:
>  >  > On Wed, Apr 16, 2008 at 11:33 AM, Phil Thompson
>  >  >
>  >  > <phil at riverbankcomputing.co.uk> wrote:
>  >  > > On Wednesday 16 April 2008, Arve Knudsen wrote:
>  >  > >  > Phil, any comment on this?
>  >  > >  >
>  >  > >  > Thanks,
>  >  > >  > Arve
>  >  > >
>  >  > >  Unless you can use the ctor that takes a void* I don't see how you can
>  >  > > expect to extend the functionality of a C++ class from Python.
>  >  >
>  >  > How am I supposed to use the QVariant(int typeOrUserType, const void*
>  >  > copy) constructor from Python? The documentation refers to
>  >  > sip.voidptr, which I know nothing about, and  to use qVariantFromValue
>  >  > which isn't defined.
>  >  >
>  >  > I need to store objects of a custom class in QVariants, with a certain
>  >  > type code (QVariant::Type). The reason I need to do this is that
>  >  > QItemEditorFactory is parameterized on QVariant::Type.
>  >  >
>  >  > Arve
>  >
>  >
>  >
>  > If you look at qmetatype.h, you'll see that it should be possible to create a
>  >  mechanism to register custom python classes as QVariant types.  You just need
>  >  to implement Constructor/Destructor methods that call Py_INCREF/Py_DECREF.
>  >  Then for each custom python type call QMetaType::registerType(...).  This
>  >  would need to be implemented in c++ with a python interface.
>  >
>  >  You could then write a custom QVariant constructor that detects if the python
>  >  object's type is registered, and automatically call the QVariant(int
>  >  type,void*) ctor, or throws an exception for non-registered types.
>
>
> So I would *have to* do this in C++? Ugh.

Phil: Can you confirm that I have to do this via C++?

Thanks,
Arve