From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <zsh-workers-return-30038-mason-zsh=primenet.com.au@zsh.org>
Received: (qmail 21688 invoked by alias); 21 Dec 2011 03:05:37 -0000
Mailing-List: contact zsh-workers-help@zsh.org; run by ezmlm
Precedence: bulk
X-No-Archive: yes
List-Id: Zsh Workers List <zsh-workers.zsh.org>
List-Post: <mailto:zsh-workers@zsh.org>
List-Help: <mailto:zsh-workers-help@zsh.org>
X-Seq: 30038
Received: (qmail 8985 invoked from network); 21 Dec 2011 03:05:35 -0000
X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on f.primenet.com.au
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE
	autolearn=ham version=3.3.2
Received-SPF: none (ns1.primenet.com.au: domain at closedmail.com does not designate permitted sender hosts)
From: Bart Schaefer <schaefer@brasslantern.com>
Message-id: <111220190511.ZM11868@torch.brasslantern.com>
Date: Tue, 20 Dec 2011 19:05:11 -0800
In-reply-to: <4EF13FBA.8080803@eastlink.ca>
Comments: In reply to Ray Andrews <rayandrews@eastlink.ca>        "bug" (Dec
 20,  6:08pm)
References: <4EF13FBA.8080803@eastlink.ca>
X-Mailer: OpenZMail Classic (0.9.2 24April2005)
To: zsh-workers@zsh.org
Subject: Re: bug
MIME-version: 1.0
Content-type: text/plain; charset=us-ascii

On Dec 20,  6:08pm, Ray Andrews wrote:
}
} function z
} {
} var=$1
} echo "var:/${1:0:1}/${1:1:1}/${1:2:1}/"
} echo "var:/${var:0:1}/${var:1:1}/${var:2:1}/"
} 
} }
} 
} $ z abcde
} 
} var: /a/a/b/
} var: /a/b/c/
} 
} How can that be correct?

I'm still not sure it's correct, but this explains why it happens:

     For further compatibility with other shells there is a special case
     for array offset 0.  This usually accesses to the first element of
     the array.  However, if the substitution refers the positional
     parameter array, e.g. $@ or $*, then offset 0 instead refers to
     $0, offset 1 refers to $1, and so on.  In other words, the
     positional parameter array is effectively extended by prepending
     $0.  Hence ${*:0:1} substitutes $0 and ${*:1:1} substitutes $1.

So :0:1 is acting on the invisible $0 even though the reference is to
an individual positional parameter rather than to the positional array.