Re: [RFA 02/14] Change event code to use gdbpy_reference

[Pedro Alves <palves at redhat dot com>]

On 11/11/2016 12:09 AM, Pedro Alves wrote:
> On 11/07/2016 05:47 AM, Tom Tromey wrote:
>>  PyObject *
>>  create_breakpoint_event_object (PyObject *breakpoint_list, PyObject *first_bp)
>>  {
>> -  PyObject *breakpoint_event_obj =
>> -      create_stop_event_object (&breakpoint_event_object_type);
>> +  gdbpy_reference breakpoint_event_obj
>> +    (create_stop_event_object (&breakpoint_event_object_type));
>>  
> 
>> - fail:
>> -  Py_XDECREF (breakpoint_event_obj);
>> -  return NULL;
>> +  return breakpoint_event_obj.release ();
>>  }
> 
> Wouldn't it better to make these create_foo functions return a
> gdbpy_reference ?  Then at the call site you'd use std::move instead
> of reset (when assigning to an existing lval):
> 
>       stop_event_obj = std::move (create_breakpoint_event_object (list.get (),
> 							          first_bp));

Err, not even std::move would be necessary, of course, 
since the function's return would be an rvalue in this context already.

So you'd just do:

  stop_event_obj = create_breakpoint_event_object (list.get (), first_bp));

That could be done after this series lands, in any case.

> The advantage of following such a principle is that it makes it impossible
> for callers to forget to manage the result with a gdbpy_reference, since
> assigning the return to a raw PyObject * won't compile.

Thanks,
Pedro Alves