[PATCH v2 06/10] rtc: add rtc command

[Simon Glass]

Hi Rasmus,

On Tue, 2 Jun 2020 at 03:13, Rasmus Villemoes
<rasmus.villemoes at prevas.dk> wrote:
>
> On 31/05/2020 16.07, Simon Glass wrote:
> > Hi Rasmus,
> >
> > On Tue, 19 May 2020 at 16:01, Rasmus Villemoes
> > <rasmus.villemoes at prevas.dk> wrote:
> >>

[..]

> >> +int do_rtc(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
> >> +{
> >> +       static int curr_rtc = 0;
> >> +       struct udevice *dev;
> >> +       int ret, idx;
> >> +
> >> +       if (argc < 2)
> >> +               return CMD_RET_USAGE;
> >> +
> >> +       argc--;
> >> +       argv++;
> >> +
> >> +       if (!strcmp(argv[0], "list")) {
> >
> > It is comment in U-Boot to just check the letters that are needed. So
> > here you could do (*argv[0] == 'l')
>
> Yes, and I consider that an anti-pattern. It makes it impossible to
> later introduce another (sub)command which starts with a
> previously-unique prefix. Now, if that "just type a unique prefix"
> wasn't official, so scripts were always supposed to use the full names,
> it wouldn't be that big a problem (scripts written for later versions of
> U-Boot, or U-Boots configured with more (sub)commands, could still fail
> silently if used on an earlier U-Boot or one with fewer (sub)commands
> instead of producing a "usage" error message), but
> https://www.denx.de/wiki/view/DULG/UBootCommandLineInterface explicitly
> mentions that as a feature (and says h can be used for help, which it
> can't when the hash command is built in, perfectly exemplifying what I'm
> talking about).

Hah funny. Using an abbreviation is only possible if no other command
starts with the same leters.

It is certainly very risky to use abbreviations in scripts. I would
not recommend it. Abbreviations are for interactive use. If you have
auto-completion on you can use tab.

But here we are talking about a sub-command, which is a bit more
controlled, in that it doesn't depend on what other commands the user
enables.

Anyway, it's up to you what you want to do here.

Regards,
Simon