Re: [Qemu-devel] [PATCH v6 3/7] qemu.py: use python logging system

[Amador Pahim]

On Wed, Aug 16, 2017 at 8:17 AM, Markus Armbruster <address@hidden> wrote:
> Eduardo Habkost <address@hidden> writes:
>
>> On Tue, Aug 15, 2017 at 10:10:12AM +0200, Markus Armbruster wrote:
>>> Please spell "Python" with a capital "P" (it's a proper name).
>>>
>>> Amador Pahim <address@hidden> writes:
>>>
>>> > Let's provide extra control and flexibility by using python logging
>>> > system instead of print and/or sys.std*.write().
>>> >
>>> > Signed-off-by: Amador Pahim <address@hidden>
>>>
>>> How exactly does this change error messages?
>>>
>>> Is logging the right tool to report errors to the human user?  I'm
>>> asking because logging and error reporting are generally separate
>>> things.  Example: a program runs into a recoverable error.  It logs the
>>> error, but does not report it.
>>>
>>> Is reporting errors to stderr the right thing to do for library class
>>> QEMUMachine?  I doubt it.  Libraries throw exceptions and let their
>>> users decide how to handle them.
>>
>> I believe the "qemu received signal" event is supposed to be
>> logged, not necessarily reported.  Callers can then choose where
>> the log messages should go (scripts could choose to send them
>> directly to stderr if verbose or debugging mode is enabled).  We
>> don't even need an exception for it: we can let callers check
>> exitcode() and decide what to do about the QEMU exit code.
>
> Makes sense.
>
>> The send_fd_scm() messages, on the other hand, could become
>> exceptions, and don't need the logging system at all.
>
> I think we all agree that printing to stderr is not a good idea for this
> library class.  Instead of a blanket conversion to logging without
> further explanation, I'd like to see cleanup with rationale such as
> yours.

Ok.