Re: [Qemu-devel] [RFC, PATCH] Add -Wstrict-prototypes, maybe later -Wmissing-prototypes

[Avi Kivity <avi@qumranet.com>]

Anthony Liguori wrote:
> Laurent Vivier wrote:
>> Le lundi 11 août 2008 à 14:22 -0500, Anthony Liguori a écrit :
>>  
>> but using "void (*handler)(int argc, char** argv)" avoids the switch:
>>
>> switch(nb_args) {
>>     case 0:
>>         cmd->handler();
>>         break;
>>     case 1:
>>         cmd->handler(args[0]);
>>         break;
>> ...
>> }
>>
>> becomes
>>
>> cmd->handler(nb_args, args);
>>   
>
> And then every monitor command changes from:
>
> void do_eject(int force, char *device)
> {
>     ...
> }
>
> to:
>
> void do_eject(int argc, char **argv)
> {
>   char *device;
>   int force = 0;
>
>   if (argc == 2) {
>     if (strcmp(argv[0], "-f") == 0) {
>         force = 1;
>         device = argv[1];
>     } else {
>         term_printf("bad option %s\n", argv[0]);
>         return;
>     }
>  } else if (argc == 1) {
>      device = argv[0];
>  } else {
>      term_printf("bad number of options\n");
>      return;
>  }
>
>  ...
> }
>
> Consider multiplying that by all of the possible monitor commands, and 
> it's totally not worth it.
>


I forgot about non-string args.  So the transformation would be:

void do_eject(void **args)
{
    int *force = *(int *)args[0];
    const char *device = *(const char **)args[1];

   ...
}

But this isn't really an improvement, apart from dropping the ugly switch.

(maybe a union:

typedef union {
    int i;
    const char *s;
    ...
} Arg;

void do_eject(const Args *args)
{
    int force = args++->i;
    const char *device = args++->s;

    ...
}

)

-- 
error compiling committee.c: too many arguments to function