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To: Stephane Chazelas <stephane_cHaZelaS@yahoo.fr>
Cc: Zsh hackers list <zsh-workers@sunsite.dk>
Subject: Re: array expansion (Was: [bug-report] brace_ccl and $'\0' in ranges) 
In-reply-to: "Stephane Chazelas"'s message of "Tue, 07 Oct 2003 10:14:17 +0200."
             <20031007081417.GA418@pcchazelas.free.fr> 
Date: Fri, 10 Oct 2003 21:16:57 +0100
From: Peter Stephenson <pws@pwstephenson.fsnet.co.uk>
Message-Id: <20031010201658.0441A84E0@pwstephenson.fsnet.co.uk>

Stephane Chazelas wrote:
> I've tried subscribing my other address at yahoo.fr, let's see.

Didn't seem to work.  Here's what SpamAssassin says about your mail; it
ends up with a sizeable negative score, so I doubt if this helps.

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> What is the historical reason why
> 
> array=(1 "" "3 4")
> cmd $array
> # is cmd 1 "3 4"
> 
> the empty arguments are stripped.

I suppose it's because the same thing happens with individual scalars.
An array element basically behaves as a scalar.  (This is similar to other
shells.)

> I understand that zsh arrays are not hashes as in ksh or bash,
> and always start at index 1, even if you only define array[12],
> but wasn't it simpler to have:
> 
> array=(1 "" "3 4")
> cmd $array
> # is cmd 1 "" "3 4"
> # and
> cmd ${array:#}
> # is cmd 1 "3 4"
> 
> I more often need to use "${array[@]}" expansion, than the
> $array one.
> Note that the user guide is clear about this behavior, but not
> the manual. It says:
> 
> | A subscript of the form `[*]' or `[@]' evaluates to all elements
> | of an array; [...] When an array parameter is referenced as
> | `$NAME' (with no subscript) it evaluates to `$NAME[*]'
> 
> no reference about the empty elements implicit filtering.
> 
> Same thing for
> var=
> cmd $var
> # turned into cmd
> # instead of  cmd ""
> cmd ${var+$var}
> # would have made it.
> 
> I end up having to use "$var" and "${array[@]}" everywhere as in
> other shells.

Yes, that's the long and short of it, if you need to preserve empty
array elements.

-- 
Peter Stephenson <pws@pwstephenson.fsnet.co.uk>
Work: pws@csr.com
Web: http://www.pwstephenson.fsnet.co.uk