[pygtk] Re: Overriding GObject methods in Python

[Gustavo J. A. M. Carneiro]

On Sex, 2006-11-24 at 11:29 +0100, Hrvoje Nikšić wrote:
> On Fri, 2006-11-24 at 10:33 +0100, Murray Cumming wrote:
> > On Thu, 2006-11-23 at 12:27 +0100, Hrvoje Nikšić wrote: 
> > [snip] 
> > > The problem is that the fields of XyzClass and its descendants are
> > C 
> > > struct members, as inaccessible to Python code as any field of a C 
> > > struct, at least without heavy ctypes hackery. 
> > [snip]
> > 
> > But I guess that pygtk (like other bindings) has a standard way of 
> > wrapping these, because they are needed in order to implement custom 
> > GtkTreeModels or GtkCellRenderers, among other things.
> 
> As far as I can tell by looking at gtk/pygtkcellrenderer.c, PyGTK allows
> overriding by creating a "stub class" PyGtkGenericCellRenderer that
> inherits GtkCellRenderer and overrides its C methods with its own
> methods that call into Python.  GtkTreeModel is handled exactly the
> same.
> 
> While this approach works for a specific class, it requires writing
> non-trivial glue code for each class that needs to be subclassed.  It
> doesn't allow a Python programmer to subclass a given GObject class
> directly from Python.

  The GenericGtkFooBar are the old way of doing this and are deprecated.
Nowadays you can subclass any gtk.XxxCellRenderer and override specific
vfuncs.  Take a look at (define-virtual ...) blocks in the .defs.

  Regards,

-- 
Gustavo J. A. M. Carneiro
<gjc at inescporto.pt> <gustavo at users.sourceforge.net>
The universe is always one step beyond logic.