Re: [vsipl++] [patch] Find & use native C MPI

[Nathan Myers <ncm@xxxxxxxxxxxxxxxx>]

On Mon, Dec 26, 2005 at 02:16:08PM -0800, Mark Mitchell wrote:
> Nathan (Jasper) Myers wrote:
>           you should not use this option.]),
> >    [case x"$enableval" in
> > -    xyes) maintainer_mode=true ;;
> > -    xno)  maintainer_mode= ;;
> > -    *)   AC_MSG_ERROR([Invalid argument to --enable-maintainer-mode.])
> > +    (xyes) maintainer_mode=true ;;
> > +    (xno)  maintainer_mode= ;;
> > +    (*)   AC_MSG_ERROR([Invalid argument to --enable-maintainer-mode.])
> 
> I didn't know about the (...) syntax, although I see it's certainly
> documented in bash.  Is is valid with all shells?
> 
> I haven't see anyone use that in an autoconf script before; my concern
> is that this might make the configure script less portable.

I started using it when I got bizarre syntax errors from bash, on a 
particular script, if I didn't use it.  Pdksh (or was it Bell Labs ksh?) 
also reported an ambiguity, and helpfully suggested the "()" notation 
to resolve it.  I haven't encountered any sh that doesn't support it, 
going back to AT&T sh, and including zsh (ack! spit!) and ash.  I added 
the "(" in this instance while tracing a bracketing problem, testing a 
configure script, that turned out to be a missing "fi".

Unfortunately the script that provoked the error messages is lost,
but it was less than four years ago.  All I recall now is that the
pattern involved was only a little more complicated than a literal 
string.  The cases above are obviously canonical and so could not 
trigger the failure, but it seems to me more defensive to promote 
the "()" notation.  

Nathan Myers
ncm