[Libguestfs] [PATCH] fish: show synopsis if command syntax is wrong

[Hu Tao]

On Mon, Dec 01, 2014 at 09:44:41AM +0000, Richard W.M. Jones wrote:
> On Mon, Dec 01, 2014 at 02:42:54PM +0800, Hu Tao wrote:
> > On Mon, Dec 01, 2014 at 10:25:51AM +0800, Hu Tao wrote:
> > > On Fri, Nov 28, 2014 at 03:00:39PM +0100, Pino Toscano wrote:
> > > > On Friday 28 November 2014 17:55:51 Hu Tao wrote:
> > > > > This patch lets guestfish show command synopsis if the syntax of command issued
> > > > > by user is wrong, rather than telling user that the number of parameters is wrong.
> > > > 
> > > > The idea seems sound to me.
> > > > 
> > > > Shouldn't that be done also for fish commands? If so, just make
> > > > "synopsis" a function taking args and optargs, and use it in both
> > > > places.
> > > 
> > > fish commands do not have args and optargs in their definitions in file
> > > actions.ml. Also, fish commands' synopsises are printed out by inline
> > > codes, see run_alloc() for an example.
> > > 
> > > Surely we can reconstruct fish commands' definitions to take advantage
> > > of the auto-generation of synopsis done in this patch, but that can be
> > > another patch. I'll add this to my todo list.
> > 
> > After some dig, the only problem I don't know how to solve is commands
> > with variable-length parameters, such as copy-in. Its synopsis is:
> > 
> >   copy-in local [local ...] /remotedir
> > 
> > At first think its style could be:
> > 
> >   "style = RErr, [StringList "local"], [];
> > 
> > But it seems the syntax corresponding to StringList is:
> > 
> >   copy-in "local local" /remotedir
> > 
> > e.g. its a one parameter of List type, but not several parameters. Any
> > ideas?
> 
> As you've discovered, guestfish commands don't use the 'style' field
> at all.  Each command receives an argc/argv list of strings and parses
> it however it wants to.  It's not restricted by the usual rules for
> other API functions and so can use variable length lists of arguments.
> 
> So there is no way to get from the struct in actions.ml to a synopsis.

Okay. Thanks for your clarification!

Regards,
Hu