[pygtk] Re: Overriding GObject methods in Python

[Hrvoje Nikšić]

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.