[PyQt] PyQt4 question

[Detlev Offenbach]

On Sonntag, 27. Mai 2007, Phil Thompson wrote:
> On Sunday 27 May 2007 1:10 pm, Detlev Offenbach wrote:
> > On Sonntag, 27. Mai 2007, Phil Thompson wrote:
> > > On Sunday 27 May 2007 12:37 pm, Detlev Offenbach wrote:
> > > > 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().instanc
> > > > > > > > > >es () ) 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.
> > >
> > > So that's what you put in your conversion code in your
> > > QDesignerFormEditorPluginInterface class.
> >
> > I tried that before I posted to this list, but it didn't work. Phil, can
> > you give a little help?
>
> Post what you tried.

I tried it with the following code:

%ModuleHeaderCode
#include <qobject.h>
%End

class QDesignerFormEditorPluginInterface
{

%TypeHeaderCode
#include <abstractformeditorplugin.h>
%End

%ConvertToSubClassCode
    if ( (qobject_cast<QDesignerFormEditorPluginInterface*>(sipCpp)) )
        sipClass = sipClass_QDesignerFormEditorPluginInterface;
    else
        sipClass = NULL;
%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;
};

However, that code doesn't even compile because at this place, 
QDesignerFormEditorPluginInterface isn't derived from QObject. It seems, that 
this is a mixin class, that QDesignerPluginManager takes care of and returns 
a QObject.

It seems, that I'm stuck here.

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