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Re: while alias

X-seq: zsh-users 28336
From: Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>
To: Pier Paolo Grassi <pierpaolog@xxxxxxxxx>
Cc: Zsh-Users List <zsh-users@xxxxxxx>
Subject: Re: while alias
Date: Mon, 7 Nov 2022 22:13:53 -0800
Archived-at: <https://zsh.org/users/28336>
In-reply-to: <CAP+y1xA2rYkSgO2Xpo7NfDKeJwE5+Gc8BdFCsw8b8Mw0RGBvsg@mail.gmail.com>
List-id: <zsh-users.zsh.org>
References: <CAP+y1xA2rYkSgO2Xpo7NfDKeJwE5+Gc8BdFCsw8b8Mw0RGBvsg@mail.gmail.com>

On Mon, Nov 7, 2022 at 5:57 PM Pier Paolo Grassi <pierpaolog@xxxxxxxxx> wrote:
>
> Hello, I have the following alias defined:
>
> WI='while {read -r it; ! [[ $? -ne 0 && -z $it ]]}'
>
> that works fine except in command substitution:

Put spaces around your braces.

alias WI='while { read -r it; ! [[ $? -ne 0 && -z $it ]] }'

Aliases in command substitutions are parsed by a complicated dance
requiring that they be expanded and then backtracked over and then
re-parsed.  The character count for the "{" and/or "}" tokens is off
by one for the backtracking step when they don't have surrounding
whitespace.  (Leaving it to PWS, who choreographed this dance number,
to fix the footwork if possible.)

Follow-Ups:
- Re: while alias
  - From: Peter Stephenson

References:
- while alias
  - From: Pier Paolo Grassi

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