Re: Bug in case stmt with '('

[Peter Stephenson <pws@xxxxxx>]

schaefer@xxxxxxxxxxxxxxxxxxxxxxx wrote:
> Given the choice of:
> 
> 1.  The "current" behavior, i.e. spaces ARE significant only when the
>     optional leading paren is there;
> 2.  The POSIX behavior, i.e. spaces are not significant in case patterns;
> 3.  Spaces are never significant in glob patterns anywhere.
> 
> I'll take (2) before I'll take (3).  My solution is equivalent to (2),
> because it makes the spaces insignificant whether or not the opening
> paren is there.

This seems to me the best solution.  It seems to create the minimal
disruption to existing zsh users and to would-be POSIX users.
Changing glob semantics more widely worries me --- even if done
logically.  Shells just aren't logical anyway.

> I can't find any case where zsh doesn't permit '(' to be a glob metachar.

Actually, there's one place we had to handle syntactically specially:

[[ ($foo = (bar|rab)) ]]

The first and matching `(' do grouping, then following the `=' zsh has
to be told to expect glob patterns.  I've never seen a problem with
this, though, and the upshot is that `(' does pattern matching when
you want it to.


On something which is related, I've never been quiet happy with this:

[ ( foo = bar ) ]

(note no globbing metacharacters inside the parentheses).  As test is
an ordinary builtin, it simply gets called with the single argument `(
foo = bar )' --- the parentheses are not stripped, which has non-zero
length, so the test is true.  In fact, parentheses here are
effectively not treated as glob metacharacters.

I felt rather guilty about this: some time ago I allowed spaces inside
parentheses because I couldn't think of a good reason not to, and
because it seemed to work better with glob modifiers --- things like
*(:s/foo/bar/) --- which appeared in the same patch, rather than from
any fundamental syntactical reason.  Before, the shell would have
reported a syntax error on the above test and the user would have
known to quote the parentheses.  This is what ksh88 does.  Perhaps it
should be subject to nomatch testing (which it isn't at the moment),
perhaps to stripping of the parentheses, too.

-- 
Peter Stephenson <pws@xxxxxx>       Tel: +49 33762 77366
WWW:  http://www.ifh.de/~pws/       Fax: +49 33762 77330
Deutches Electronen-Synchrotron --- Institut fuer Hochenergiephysik Zeuthen
DESY-IfH, 15735 Zeuthen, Germany.