[PyQt] PyQt4 question

[Detlev Offenbach]

On Sonntag, 27. Mai 2007, Phil Thompson wrote:
> On Sunday 27 May 2007 11:50 am, Detlev Offenbach wrote:
> > On Sonntag, 27. Mai 2007, Phil Thompson wrote:
> > > On Saturday 26 May 2007 9:07 pm, Detlev Offenbach wrote:
> > > > On Samstag, 26. Mai 2007, Phil Thompson wrote:
> > > > > On Saturday 26 May 2007 7:58 pm, Detlev Offenbach wrote:
> > > > > > On Samstag, 26. Mai 2007, Phil Thompson wrote:
> > > > > > > On Saturday 26 May 2007 4:52 pm, Detlev Offenbach wrote:
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > is there a PyQt equivalent to "qobject_cast<T*>(object)"?
> > > > > > >
> > > > > > > sip.cast()?
> > > > > > >
> > > > > > > But it shouldn't be necessary if the sub-class conversion code
> > > > > > > has been properly implemented.
> > > > > >
> > > > > > How do I do that. I haven't wrapped complicated stuff like this
> > > > > > so far. The situation is as follows. I have the following code:
> > > > > >
> > > > > >
> > > > > > self.plugins.extend(self.designer.pluginManager().instances())
> > > > > > for plugin in self.plugins:
> > > > > >             if isinstance(plugin,
> > > > > > QDesignerFormEditorPluginInterface): if not
> > > > > > plugin.isInitialized(): plugin.initialze(self.designer)
> > > > > >
> > > > > >
> > > > > > "self.designer.pluginManager().instances()" returns a list of
> > > > > > QObject. The first if statement shall check, wether the returned
> > > > > > QObject is of type QDesignerFormEditorPluginInterface. In C++ you
> > > > > > would do it with code like
> > > > > >
> > > > > > if ( (qobject_cast<QDesignerFormEditorPluginInterface*>(plugin))
> > > > > > )
> > > > > >
> > > > > > How can the problem be solved with PyQt4 and Python?
> > > > > >
> > > > > > Note: self.designer.pluginManager() returns an object of type
> > > > > > QDesignerPluginManager.
> > > > >
> > > > > The wrapper for QDesignerFormEditorPluginInterface must define
> > > > > some %ConvertToSubClassCode which will use RTTI provided by the
> > > > > instance to identify the right Python type object. See how PyQt
> > > > > does it for QObject and QEvent. If the instance doesn't provide any
> > > > > RTTI then you're stuck.
> > > >
> > > > Mustn't the %ConvertToSubClassCode go into the more general class
> > > > (e.g. QObject)?
> > >
> > > No - just in a QObject sub-class in the module.
> > >
> > > > Is there a way to extend the QObject wrapper?
> > >
> > > That's what sip does under the covers.
> >
> > I am stuck at the moment due to my lack of sip know how. Below is the
> > wrapper code in question. How does the %ConvertToSubClassCode have to be?
> >
> > -------------------------------------------------------------------------
> >-- - class QDesignerFormEditorPluginInterface
> > {
> >
> > %TypeHeaderCode
> > #include <abstractformeditorplugin.h>
> > %End
> >
> > public:
> >     virtual ~QDesignerFormEditorPluginInterface();
> >
> >     virtual bool isInitialized() const = 0;
> >     virtual void initialize(QDesignerFormEditorInterface *core) = 0;
> >     virtual QAction *action() const = 0;
> >
> >     virtual QDesignerFormEditorInterface *core() const = 0;
> > };
> > -------------------------------------------------------------------------
> >--
>
> What RTTI is available for the code to determine what the class really is?
> I can't see anything that is obviously suitable - in which case you are
> stuck.
>

In a C++ program one would do it with this statement

qobject_cast<QDesignerFormEditorPluginInterface*>(object)

where object is a pointer to a QObject. If the conversion code would be in 
QObject.sip, one could probably use the inherits() method of QObject.

Regards,
Detlev
-- 
Detlev Offenbach
detlev at die-offenbachs.de