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

[Markus Armbruster <armbru@redhat.com>]

Eduardo Habkost <ehabkost@redhat.com> 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 <apahim@redhat.com> 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 <apahim@redhat.com>
>> 
>> 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.