Re: [Qemu-devel] [PATCH 7/7] qemu-img: allow specifying image as a set of options args

["Daniel P. Berrange" <berrange@redhat.com>]

On Wed, Dec 23, 2015 at 03:20:18PM -0500, Paolo Bonzini wrote:
> 
> 
> ----- Original Message -----
> > From: "Daniel P. Berrange" <berrange@redhat.com>
> > To: "Paolo Bonzini" <pbonzini@redhat.com>
> > Cc: "Eric Blake" <eblake@redhat.com>, "Kevin Wolf" <kwolf@redhat.com>, qemu-block@nongnu.org, qemu-devel@nongnu.org,
> > "Markus Armbruster" <armbru@redhat.com>, "Andreas Färber" <afaerber@suse.de>
> > Sent: Wednesday, December 23, 2015 8:23:13 PM
> > Subject: Re: [Qemu-devel] [PATCH 7/7] qemu-img: allow specifying image as a set of options args
> > 
> > On Wed, Dec 23, 2015 at 07:03:34PM +0100, Paolo Bonzini wrote:
> > > 
> > > 
> > > On 23/12/2015 17:55, Daniel P. Berrange wrote:
> > > >>> > > A third option would be to keep using positional arguments, but
> > > >>> > > add a '--source-opts' *boolean* flag to indicate how to interpret
> > > >>> > > the positional arguments.  ie without --source-opts we use the
> > > >>> > > historic syntax, but with --source-opts, we assume the full
> > > >>> > > QemuOpts
> > > >>> > > syntax.
> > > >> > 
> > > >> > Oh, nice compromise. It's relatively discoverable (grep --help
> > > >> > output),
> > > >> > preserves back-compat of old scripts, and offers the full power for
> > > >> > clients that want the full power.
> > > > I've implemented this now and it makes the patches soooo much simpler
> > > > too, so an added win.
> > > 
> > > Hmm, looks like I'm a bit late, but here's another possibility: making
> > > --source-options (aka -o) take an argument, and if you specify both
> > > --source-options and the positional argument, the latter is added as a
> > > "file" key.
> > > 
> > > This way you can do "qemu-img info --object secret... -o secret=foo
> > > iscsi://foo/".
> > 
> > This gets somewhat messy for the commands which needs to accept more
> > than one filename, eg 'compare' (2 files) and 'convert' (any number
> > of files)'.  eg if you have 3 positional file names and want to set
> > an option on the 2nd file, '-o foo=bar' is not really going to say
> > which positional file it applies to.
> 
> That would be -o/-O, like -f/-F.

That only works for two files, unless you keep inventing yet more
characters for the 3rd, 4th, ... file - 'convert' takes an arbitrary
number of files.

Regards,
Daniel
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