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Subject: Re: surprise with echo
From: =?utf-8?Q?Lawrence_Vel=C3=A1zquez?= <larryv@macports.org>
In-Reply-To: <141218190653.ZM16331@torch.brasslantern.com>
Date: Thu, 18 Dec 2014 22:20:10 -0500
Cc: zsh-users@zsh.org
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References: <54937E5B.2020008@eastlink.ca> <141218190653.ZM16331@torch.brasslantern.com>
To: Ray Andrews <rayandrews@eastlink.ca>
X-Mailer: Apple Mail (2.1993)

On Dec 18, 2014, at 10:06 PM, Bart Schaefer <schaefer@brasslantern.com> =
wrote:

> On Dec 18,  5:24pm, Ray Andrews wrote:
>=20
> } Can that be prevented?
>=20
> Only by turning off the option, or by doing e.g. ${@:-''} so that the
> expansion is the empty string rather than the empty array.

Also note that "preventing" it would amount to treating an empty array
the same as an array containing a single null value, which is currently
not the case:

    % emulate zsh && setopt RC_EXPAND_PARAM
    % foo=3D()
    % echo "abc${foo[*]}def"
    abcdef
    % echo "abc${foo[@]}def"

    % foo=3D('')
    % echo "abc${foo[*]}def"
    abcdef
    % echo "abc${foo[@]}def"
    abcdef

You're making quite a few assumptions about how positional parameters
and array substitution work. For instance, the fact that you're using
double quotes (which affects the expansion of $foo[*] versus $foo[@]) is
clouding your understanding of how RC_EXPAND_PARAM works. Observe:

    % emulate zsh && setopt RC_EXPAND_PARAM
    % foo=3D()
    % echo "abc${foo[*]}def"
    abcdef
    % echo abc${foo[*]}def

    %

Please read zshparam(1).

vq=