From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <zsh-workers-return-6039-mason-zsh=primenet.com.au@sunsite.auc.dk>
Received: (qmail 584 invoked from network); 14 Apr 1999 17:28:08 -0000
Received: from sunsite.auc.dk (130.225.51.30)
  by ns1.primenet.com.au with SMTP; 14 Apr 1999 17:28:08 -0000
Received: (qmail 10317 invoked by alias); 14 Apr 1999 17:27:58 -0000
Mailing-List: contact zsh-workers-help@sunsite.auc.dk; run by ezmlm
Precedence: bulk
X-No-Archive: yes
X-Seq: 6039
Received: (qmail 10308 invoked from network); 14 Apr 1999 17:27:56 -0000
From: "Bart Schaefer" <schaefer@brasslantern.com>
Message-Id: <990414102751.ZM3847@candle.brasslantern.com>
Date: Wed, 14 Apr 1999 10:27:51 -0700
In-Reply-To: <199904120717.JAA26054@beta.informatik.hu-berlin.de>
Comments: In reply to Sven Wischnowsky <wischnow@informatik.hu-berlin.de>
        "Re: BUG: zsh-3.1.5-pws-14: parameter expansion not working properly" (Apr 12,  9:17am)
References: <199904120717.JAA26054@beta.informatik.hu-berlin.de>
X-Mailer: Z-Mail (4.0b.820 20aug96)
To: zsh-workers@sunsite.auc.dk
Subject: Re: BUG: zsh-3.1.5-pws-14: parameter expansion not working properly
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii

On Apr 12,  9:17am, Sven Wischnowsky wrote:
} Subject: Re: BUG: zsh-3.1.5-pws-14: parameter expansion not working proper
}
} The rule of thumb is now that one should use the `(@)' flag whenever
} the thing is in double quotes and one wants to work on arrays.

When I first saw the patch that introduced that change, I thought that
introducing the extra consistency sounded like a good thing.

	bar=(xa)
	print -l "${${(@)bar}[1]}" "${(@)${bar}[1]}"

Zsh 3.0.5 prints

	x
	x

But 3.1.5-pws-14 prints

	x
	xa

which is nice, because you can tell a singleton array from a scalar.

Now that I've seen/used it in practice a few times, I'm not so sure any
more.  The more radical change, and one which bothers me a lot, is the
effect when the array has more than one element:

	foo=(xa yb zc)
	print -l "${${(@)foo}[1]}" "${(@)${foo}[1]}"

Zsh 3.0.5 prints

	xa
	x

But 3.1.5-pws-14 prints

	x
	xa

That's completely reversed the semantics, and thus is a serious problem.

Another difficulty is that (@) has to be repeated at *every* level of a
nested expansion, from the innermost ${...} at which an array is desired
all the way to the outermost braces.

	"${${${${(@)foo}}}}"		== "$foo[@]"

To get the equivalent effect now, having to write

	"${(@)${(@)${(@)${(@)foo}}}}"	== "$foo[@]"

is error-prone and just plain annoying.  There must be a better way.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com