bug#141: Process sentinel not called in batch mode

[Stefan Monnier]

>> >> >> This side I understand, but what about the other: why should we not
>> >> >> check process status in the case where we are not redisplaying?
>> >> 
>> >> > Because Emacs generally looks at process output only when it's idle?
>> >> 
>> >> I don't follow: we're talking about when should
>> >> wait_reading_process_output check status_notify.
>> >> 
>> >> So to repeat/rephrase my question: why doesn't
>> >> wait_reading_process_output call status_notify when it is passed a zero
>> >> do_display?
>> 
>> > Sorry, let me explain my line of thought in more detail: Emacs only
>> > does a redisplay when it is idle.  Emacs also checks input from
>> > subprocesses when it is idle.  If we are not in redisplay, it means
>> > Emacs is not idle, and so it makes sense not to check for subprocess
>> > output at that time.
>> 
>> > Does this make any sense?
>> 
>> But if we're in wait_reading_process_output, that means that idle or
>> not, we're checking for process output, so why not check for process
>> status changes as well?

> Because status_notify has a side effect of triggering redisplay.

Thanks.  Now it makes a lot more sense.  Please add a corresponding
comment on the do_display check.


        Stefan