Re: M4 syntax $11 vs. ${11}

[Ralf Wildenhues]

Hello Eric, all,

* Eric Blake wrote on Sun, Jan 28, 2007 at 06:05:48AM CET:
> 
>       * lib/m4sugar/m4sugar.m4: Cripple ${1} expansion in M4 2.0 for
>       portability with 1.4.x behavior.
>       * doc/autoconf.texi (Quoting and Parameters): New section.
>       (Quotation and Nested Macros): Touch up example.
>       * NEWS: Document the new limitation on user macros not exceeding
>       $9.
[...]

This makes things inconsistent.  Quoting `Coding Style':

| Otherwise, the closing bracket would be hidden inside a `#'-comment,
| breaking the bracket-matching highlighting from Emacsen.  Note the
| preferred style to escape from M4: `$[1]', address@hidden', etc.  Do not 
escape
| when it is unnecessary.  Common examples of useless quotation are
| `[$]$1' (write `$$1'), `[$]var' (use `$var'), etc.  If you add
| portability issues to the picture, you'll prefer `${1+"address@hidden"}' to
| `"[$]@"', and you'll prefer do something better than hacking Autoconf
| `:-)'.

The Coding Style ends up being inconsistent with
  $[#]                  where it's necessary to quote the hash,
  $[1]                  where either character could be quoted,
  [$]{1...}  vs.  $[{1...}]  vs.  $[{]1...}
                        where the first is inconsistent with the
                        previous examples, and the others are ugly,

and is not applied throughout the manual (see the `${1+"address@hidden"}' at the
end of the quoted paragraph).

IMHO, it's not a good idea to not "practice what we preach" in any
direction: either have the code be more cautious than the documentation,
or vice versa.

(But maybe you have arrived at another iteration of the patch already,
obsoleting my comments; I haven't seen any newer patch, though.)

Cheers,
Ralf