[PyQt] Construct QVariant from object of user type

[Phil Thompson]

On Friday 18 April 2008, Arve Knudsen wrote:
> 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++?

I thought I already had in the above.

Phil