Re: [Qemu-devel] [PATCH 06/29] monitor: New format for handlers argument types

[Luiz Capitulino <lcapitulino@redhat.com>]

On Mon, 24 Aug 2009 18:21:17 +0200
Markus Armbruster <armbru@redhat.com> wrote:

> Luiz Capitulino <lcapitulino@redhat.com> writes:
> 
> > Current handlers argument types, as defined in qemu-monitor.hx file,
> > are a sequence of chars where each one represents one argument type
> > of the command handler. The number of chars is also used to know how
> > many arguments a given handler accepts.
> >
> > This commit defines a new format, which makes mandatory the use of
> > a name for each argument.
> >
> > For example, do_eject() command handler is currently defined as:
> >
> > { "eject", "-fB", do_eject, ... }
> >
> > With the new format it becomes:
> >
> > { "eject", "force:-f,filename:B", do_eject, ... }
> >
> > This way the Monitor will be capable of setting up a dictionary, using
> > each argument's name as the key and the argument itself as the value.
> >
> > This commit also adds two new functions: key_get_info() and
> > next_arg_type(), both are used to parse the new format.
> >
> > Currently key_get_info() consumes the 'key' part of the new format and
> > discards it, this way the current parsing code is not affected by this
> > change.
> >
> > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> 
> Encoding the parameter list in a single args_type made perfect sense
> when a parameter was encoded in one or two characters.  But having
> syntax and a parser... I don't know.  Switch to an array of parameter
> descriptions that don't need to be parsed?

 I don't see how to do this w/o parsing, but anyway I think we should
be practical here and use what already exists.

> There's some overlap between args_type (machine-readable description)
> and params (human readable help text).  Could the latter be assembled
> from the former?

 I'm not sure this is desirable as the help text may have a list
of possible arguments accepted by the handler, this information is
internal to each handler and not part of args_type.

 For example, 'singlestep' has a 'option:s?' arg_type, but 'option'
has to be 'on' or 'off'.

 In the future though, we could think in ways of merging them
somehow.