This patch contains changes requested by Eli and Tom, and includes 
documentation for the new features.

> Instead of evregpy_get_nlisteners checking the list size, I think it
> would be better to have "evregpy_any_listeners_p" return a boolean, and
> then check whether the list is empty.  This may be more efficient and is
> what you want to do anyhow.
>

How about evregpy_no_listeners_p ? Fits better with the way the code was 
written.

> Sami>  +event_object *
> Sami>  +create_event_object (PyTypeObject *py_type)
> Sami>  +{
> Sami>  +  event_object *event_obj;
> Sami>  +
> Sami>  +  event_obj = PyObject_New (event_object, py_type);
> Sami>  +  if (!event_obj)
> Sami>  +    goto fail;
> Sami>  +
> Sami>  +  event_obj->dict = PyDict_New ();
> Sami>  +  if (!event_obj->dict)
> Sami>  +    goto fail;
> Sami>  +
> Sami>  +  return event_obj;
> Sami>  +
> Sami>  + fail:
> Sami>  +  Py_XDECREF (event_obj);
> Sami>  +  Py_XDECREF (event_obj->dict);
>
> Won't decrefing event_obj automatically free the dict when needed?
> I didn't look closely but maybe other create_* functions have this issue.
>

I fixed all the create_* functions and made sure the dealloc functions 
are using Py_XDECREF.

> Sami>  +static int
> Sami>  +add_new_registry (eventregistry_object **registryp, char *name)
> Sami>  +{
> Sami>  +  *registryp = create_eventregistry_object ();
> Sami>  +  if(*registryp == NULL)
>
> Newline between these lines.
> Space before open paren.
>
> Why not just return the new registry, or NULL on error?
> That would be simpler.
>

Adding the registry, and doing the needed error checking here, makes the 
calling code simpler. The calling code is what will be extended in 
future development.

>
> Sami>  +static void
> Sami>  +python_inferior_exit (struct inferior *inf)
> Sami>  +{
> Sami>  +  struct cleanup *cleanup;
> Sami>  +  LONGEST exitcode_val;
> Sami>  +  LONGEST *exit_code;
> Sami>  +
> Sami>  +  cleanup = ensure_python_env (get_current_arch (), current_language);
> Sami>  +
> Sami>  +  if (get_internalvar_integer (lookup_internalvar ("_exitcode"),&exitcode_val))
> Sami>  +    exit_code =&exitcode_val;
> Sami>  +
> Sami>  +  if (exit_code
> Sami>  +&&  emit_exited_event (exit_code)<  0)
>
> You have to initialize exit_code to NULL for this to work properly.
>

Done.

> However, I think this is pretty ugly.
> It seems like there should be a better way to get this than looking up
> a convenience variable.
>

Hmm I looked through the code to find another way but could not. 
handle_inferior_event which sets the convenience variable uses 
execution_control_state which I don't have access to.

> I think we need an event representing a thread exit.
> It is ok by me if this comes in a separate patch.
> (FWIW I have a few new events on my branch; I'll update those once this
> patch goes in.)
>

In the original patch this event was halfway between thread exit and 
inferior exit. So I decided to make it inferior exit with the intention 
on adding thread exited/created events in a future patch.

> Sami>  +  signal_event_obj->stop_signal =
> Sami>  +      (PyStringObject *) PyString_FromString (stop_signal);
>
> It is more usual to just use PyObject* everywhere, and not cast to the
> more specific types.
>
> This change should let you eliminate other casts in the patch.
>

Done. I also, updated breakpoint_event_object. I was going with the 
oposite mindset of keeping the type information until a cast is required.

> Sami>  +stop_event_object *
> Sami>  +create_stop_event_object (PyTypeObject *py_type, thread_object *thread)
> Sami>  +{
> Sami>  +  stop_event_object *stop_event_obj =
> Sami>  +      (stop_event_object *) create_event_object (py_type);
> Sami>  +
> Sami>  +  if (!stop_event_obj)
> Sami>  +    goto fail;
> Sami>  +
> Sami>  +  stop_event_obj->inferior_thread = (PyObject *) thread;
> Sami>  +
> Sami>  +  if (evpy_add_attribute ((event_object *) stop_event_obj,
> Sami>  +                          "inferior_thread",
> Sami>  +                          stop_event_obj->inferior_thread)<  0)
> Sami>  +    goto fail;
> Sami>  +
> Sami>  +
> Sami>  +  return stop_event_obj;
>
> I think it would be better to just have one cast at the end, instead of
> lots of casts in the body.
>

Hmm if I change stop_event_object* to event_object it would eliminate 
two casts but also add two. One when setting the inferior thread and one 
for returning. Same goes for all the create_* functions or should I 
change all of those to return more generic objects ?

> Sami>  +  if (bs&&  bs->breakpoint_at
> Sami>  +&&  bs->breakpoint_at->type == bp_breakpoint)
> Sami>  +    {
> Sami>  +      if (evregpy_get_nlisteners (gdb_py_events.breakpoint) == 0)
> Sami>  +	return 0;
>
> I think the short-circuiting logic should be hoisted to the top of the
> function.  This is more efficient and also lets you avoid having to
> deal with reference counting problems involving objects made earlier.
>

I moved the thread creation after the short circuiting, but I cannot be 
moved up further because we have to figure out the type of event.

> Sami>  +  /* Check if the signal is "Signal 0" or "Trace/breakpoint trap".  */
> Sami>  +  if ((strcmp (stop_signal, "0") != 0)
> Sami>  +&&  (strcmp (stop_signal, "SIGTRAP") != 0))
>
> I didn't look this up, but this seems questionable.
> Is this really how this is done?
>

I improved this by using enum target_signal and target_signal_to_name to 
convert the signal to a string when notifying python listeners. That 
looks OK IMO, but we can also create a module gdb.signal, create a pyhon 
Signal type, add Signal types for all signals to gdb.signal, and use a 
Signal object to notify python listeners.


> Sami>  +typedef struct
> Sami>  +{
> Sami>  +  PyObject *inferior_thread;
> Sami>  +  event_object event;
> Sami>  +} stop_event_object;
>
> For the inheritance scheme to work, the 'event' field has to come first.
> I didn't audit the other event object types, but please make sure they
> are all correct.
>

Corrected and checked other objects.