//====================================================================
// Descriptor __get__ implementation. A getattr on an event returns
// a "bound" event that keeps a reference to the object instance.
//====================================================================
public static IntPtr tp_descr_get(IntPtr ds, IntPtr ob, IntPtr tp)
{
EventObject self = GetManagedObject(ds) as EventObject;
EventBinding binding;
if (self == null)
{
return Exceptions.RaiseTypeError("invalid argument");
}
// If the event is accessed through its type (rather than via
// an instance) we return an 'unbound' EventBinding that will
// be cached for future accesses through the type.
if (ob == IntPtr.Zero)
{
if (self.unbound == null)
{
self.unbound = new EventBinding(self, IntPtr.Zero);
}
binding = self.unbound;
Runtime.XIncref(binding.pyHandle);
return binding.pyHandle;
}
if (Runtime.PyObject_IsInstance(ob, tp) < 1)
{
return Exceptions.RaiseTypeError("invalid argument");
}
binding = new EventBinding(self, ob);
return binding.pyHandle;
}
//====================================================================
// EventBinding -= operator implementation.
//====================================================================
public static IntPtr nb_inplace_subtract(IntPtr ob, IntPtr arg)
{
EventBinding self = (EventBinding)GetManagedObject(ob);
if (Runtime.PyCallable_Check(arg) < 1)
{
Exceptions.SetError(Exceptions.TypeError,
"invalid event handler"
);
return(IntPtr.Zero);
}
if (!self.e.RemoveEventHandler(self.target, arg))
{
return(IntPtr.Zero);
}
Runtime.Incref(self.pyHandle);
return(self.pyHandle);
}
//====================================================================
// EventBinding += operator implementation.
//====================================================================
public static IntPtr nb_inplace_add(IntPtr ob, IntPtr arg)
{
EventBinding self = (EventBinding)GetManagedObject(ob);
if (Runtime.PyCallable_Check(arg) < 1)
{
Exceptions.SetError(Exceptions.TypeError,
"event handlers must be callable"
);
return(IntPtr.Zero);
}
if (!self.e.AddEventHandler(self.target, arg))
{
return(IntPtr.Zero);
}
Runtime.XIncref(self.pyHandle);
return(self.pyHandle);
}
