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Re: [Libguestfs] [PATCH v2] fish: show synopsis if command syntax is wrong



On Mon, Dec 01, 2014 at 06:01:25PM +0000, Richard W.M. Jones wrote:
> 
> How about the following?  I've made it use a named value
> (RUN_WRONG_ARGS == -2) instead of just the magic number.

Yes, it looks better!

> 
> Also I removed an incorrect hunk from the original patch (space before
> synopsis string is required).

The space before synopsis makes the text of synopsis misaligned. I don't
know why it's required, but if it does, the patch looks good to me.

Regards,
Hu

> 
> Rich.
> 
> -- 
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
> Read my programming and virtualization blog: http://rwmj.wordpress.com
> virt-top is 'top' for virtual machines.  Tiny program with many
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> http://people.redhat.com/~rjones/virt-top

> >From 4c65e5564c525e7b4ab5d3268f37547b853c0d03 Mon Sep 17 00:00:00 2001
> From: Hu Tao <hutao cn fujitsu com>
> Date: Mon, 1 Dec 2014 18:26:12 +0800
> Subject: [PATCH] fish: show synopsis if command syntax is wrong
> 
> 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.
> 
> Signed-off-by: Hu Tao <hutao cn fujitsu com>
> ---
>  fish/cmds-gperf.h |  1 +
>  generator/fish.ml | 48 +++++++++++++++++++++++++-----------------------
>  2 files changed, 26 insertions(+), 23 deletions(-)
> 
> diff --git a/fish/cmds-gperf.h b/fish/cmds-gperf.h
> index 74db69d..bcb3b5d 100644
> --- a/fish/cmds-gperf.h
> +++ b/fish/cmds-gperf.h
> @@ -25,6 +25,7 @@
>  struct command_entry {
>    const char *name;             /* Short name. */
>    const char *help;             /* Online help. */
> +  const char *synopsis;         /* Synopsis. */
>  
>    /* The run_* function. */
>    int (*run) (const char *cmd, size_t argc, char *argv[]);
> diff --git a/generator/fish.ml b/generator/fish.ml
> index 3f53ffa..b609ce9 100644
> --- a/generator/fish.ml
> +++ b/generator/fish.ml
> @@ -98,6 +98,10 @@ let generate_fish_cmds () =
>    pr "/* Valid suffixes allowed for numbers.  See Gnulib xstrtol function. */\n";
>    pr "static const char *xstrtol_suffixes = \"0kKMGTPEZY\";\n";
>    pr "\n";
> +  pr "/* Return these errors from run_* functions. */\n";
> +  pr "#define RUN_ERROR -1\n";
> +  pr "#define RUN_WRONG_ARGS -2\n";
> +  pr "\n";
>  
>    List.iter (
>      fun { name = name } ->
> @@ -129,6 +133,7 @@ let generate_fish_cmds () =
>        pr "struct command_entry %s_cmd_entry = {\n" name;
>        pr "  .name = \"%s\",\n" name2;
>        pr "  .help = \"%s\",\n" (c_quote text);
> +      pr "  .synopsis = NULL,\n";
>        pr "  .run = run_%s\n" name;
>        pr "};\n";
>        pr "\n";
> @@ -190,6 +195,7 @@ Guestfish will prompt for these separately."
>        pr "struct command_entry %s_cmd_entry = {\n" name;
>        pr "  .name = \"%s\",\n" name2;
>        pr "  .help = \"%s\",\n" (c_quote text);
> +      pr "  .synopsis = \"%s\",\n" (c_quote synopsis);
>        pr "  .run = run_%s\n" name;
>        pr "};\n";
>        pr "\n";
> @@ -337,7 +343,7 @@ Guestfish will prompt for these separately."
>        pr "static int\n";
>        pr "run_%s (const char *cmd, size_t argc, char *argv[])\n" name;
>        pr "{\n";
> -      pr "  int ret = -1;\n";
> +      pr "  int ret = RUN_ERROR;\n";
>        (match ret with
>         | RErr
>         | RInt _
> @@ -393,30 +399,14 @@ Guestfish will prompt for these separately."
>  
>        if argc_minimum = argc_maximum then (
>          pr "  if (argc != %d) {\n" argc_minimum;
> -        if argc_minimum = 0 then (
> -          pr "    fprintf (stderr, _(\"%%s should have no parameters\\n\"), cmd);\n";
> -        ) else (
> -          pr "    fprintf (stderr, ngettext(\"%%s should have %%d parameter\\n\",\n";
> -          pr "                              \"%%s should have %%d parameters\\n\",\n";
> -          pr "                              %d),\n"
> -            argc_minimum;
> -          pr "                     cmd, %d);\n"
> -            argc_minimum;
> -        )
> +          pr "    ret = RUN_WRONG_ARGS;\n";
>        ) else if argc_minimum = 0 then (
>          pr "  if (argc > %d) {\n" argc_maximum;
> -        pr "    fprintf (stderr, ngettext(\"%%s should have at most %%d parameter\\n\",\n";
> -        pr "                              \"%%s should have at most %%d parameters\\n\",\n";
> -        pr "                              %d),\n"
> -          argc_maximum;
> -        pr "                     cmd, %d);\n"
> -          argc_maximum;
> +        pr "    ret = RUN_WRONG_ARGS;\n";
>        ) else (
>          pr "  if (argc < %d || argc > %d) {\n" argc_minimum argc_maximum;
> -        pr "    fprintf (stderr, _(\"%%s should have %%d-%%d parameter(s)\\n\"), cmd, %d, %d);\n"
> -          argc_minimum argc_maximum;
> +        pr "    ret = RUN_WRONG_ARGS;\n";
>        );
> -      pr "    fprintf (stderr, _(\"type 'help %%s' for help on %%s\\n\"), cmd, cmd);\n";
>        pr "    goto out_noargs;\n";
>        pr "  }\n";
>  
> @@ -694,16 +684,28 @@ Guestfish will prompt for these separately."
>    pr "run_action (const char *cmd, size_t argc, char *argv[])\n";
>    pr "{\n";
>    pr "  const struct command_table *ct;\n";
> +  pr "  int ret = -1;\n";
>    pr "\n";
>    pr "  ct = lookup_fish_command (cmd, strlen (cmd));\n";
> -  pr "  if (ct)\n";
> -  pr "    return ct->entry->run (cmd, argc, argv);\n";
> +  pr "  if (ct) {\n";
> +  pr "    ret = ct->entry->run (cmd, argc, argv);\n";
> +  pr "    /* run function may return magic value -2 (RUN_WRONG_ARGS) to indicate\n";
> +  pr "     * that this function should print the command synopsis.\n";
> +  pr "     */\n";
> +  pr "    if (ret == RUN_WRONG_ARGS) {\n";
> +  pr "      fprintf (stderr, _(\"error: incorrect number of arguments\\n\"));\n";
> +  pr "      if (ct->entry->synopsis)\n";
> +  pr "        fprintf (stderr, _(\"usage: %%s\\n\"), ct->entry->synopsis);\n";
> +  pr "      fprintf (stderr, _(\"type 'help %%s' for more help on %%s\\n\"), cmd, cmd);\n";
> +  pr "      ret = -1;\n";
> +  pr "    }\n";
> +  pr "  }\n";
>    pr "  else {\n";
>    pr "    fprintf (stderr, _(\"%%s: unknown command\\n\"), cmd);\n";
>    pr "    if (command_num == 1)\n";
>    pr "      extended_help_message ();\n";
> -  pr "    return -1;\n";
>    pr "  }\n";
> +  pr "  return ret;\n";
>    pr "}\n"
>  
>  and generate_fish_cmds_h () =
> -- 
> 2.1.0
> 


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