Re: [Qemu-devel] [PATCH v4 0/3] chardev: Add -qmp-pretty

[Max Reitz]

On 2014-11-28 at 16:55, Markus Armbruster wrote:
> Copying Luiz.
>
> Max Reitz <address@hidden> writes:
>
> > This series does not add new functionality. Adding a QMP monitor with
> > prettily formatted JSON output can be done as follows:
> >
> > $ qemu -chardev stdio,id=mon0 -mon chardev=mon0,mode=control,pretty=on
> >
> > However, this is rather cumbersome, so this series (its first patch)
> > adds a shortcut in the form of the new command line option -qmp-pretty.
> >
> > Since the argument given to a monitor command line option (such as -qmp)
> > is parsed depending on its prefix and probably also depending on the
> > current phase of the moon, this is cleaner than trying to add a "switch"
> > to -qmp itself (in the form of "-qmp stdio,pretty=on").
> Yet another "convenience" option *groan*
>
> Why can't we simply make -qmp set pretty=on and be done with it?
> It's a convenience option, i.e. meant for humans, and why would humans
> *not* want pretty=on?

Well, pretty=on produces really long output. I prefer short output if I 
don't expect to run commands like query-block which are completely 
unreadable with pretty=off.

I personally had a really bad taste when I saw that I couldn't modify 
-qmp somehow to get it to set pretty=on optionally. But then, after 
having implemented -qmp-pretty in basically five lines (the "case" 
statement for that option and the qemu_opt_set_bool() in 
monitor_parse()), I could send the series with a clear conscience. It's 
not that there's a new convenience option which is really bad to 
maintain and will break after the first gentle blow, as it reuses all 
the code paths from -qmp, which we will keep anyway.

Since this is only in block-next, I wouldn't object to it being dropped 
and making pretty=on the default for -qmp, in principle. But I 
personally like having a convenience pretty=off option, too, because I 
as a human often actually don't want pretty=on.

Max