From: Roman Perepelitsa <roman.perepelitsa@gmail.com>
To: Bart Schaefer <schaefer@brasslantern.com>
Cc: Ray Andrews <rayandrews@eastlink.ca>, zsh-users@zsh.org
Subject: Re: Belaboring substitution syntax
Date: Thu, 17 Nov 2022 09:59:40 +0100 [thread overview]
Message-ID: <CAN=4vMovAvSK8QOJ-uMiK6ujdP+vvBF+d3SUHyX-oLNQaA30cg@mail.gmail.com> (raw)
In-Reply-To: <CAH+w=7ZFoj+0okm1EUZEsb8XqDarrSu9WDNiDxJ-Y5T-_ThD3A@mail.gmail.com>
On Thu, Nov 17, 2022 at 3:32 AM Bart Schaefer <schaefer@brasslantern.com> wrote:
>
> On Wed, Nov 16, 2022 at 6:15 AM Roman Perepelitsa
> <roman.perepelitsa@gmail.com> wrote:
> >
> > On Wed, Nov 16, 2022 at 3:09 PM Ray Andrews <rayandrews@eastlink.ca> wrote:
> > >
> > > "${array[@]}" ... Read: protect the elements of this array, do any expansions within them, but do NOT combine them ??
> >
> > No, this just expands the array to all its elements.
>
> In the base cases, you can think of it as "if I can't see it, nothing
> happens to it." The exceptions only occur when you start adding
> parameter flags like ${(e)array[@]}.
If I didn't know that ${array[@]} without quotes does not in general
expand to the array's elements, I could be confused by this exchange,
so I'll post some examples for Ray's benefit.
This does nothing (the array's content is unchanged):
array=("${array[@]}")
This may change the content of the array:
array=(${array[@]})
The content of the array is changed by this statement in two ways:
1. All empty elements are removed.
2. If sh_word_split is set, elements of the array are split on $IFS.
To demonstrate (1):
% () {
emulate -L zsh
local array=('' 'foo bar')
typeset -p array
array=(${array[@]})
typeset -p array
}
typeset -a array=( '' 'foo bar' )
typeset -a array=( 'foo bar' )
To demonstrate (2):
% () {
emulate -L zsh -o sh_word_split
local array=('' 'foo bar')
typeset -a array=( 'foo bar' )
array=(${array[@]})
typeset -p array
}
typeset -a array=( '' 'foo bar' )
typeset -a array=( foo bar )
In short, "${array[@]}" expands to array elements just like "$scalar"
expands to the scalar's value. Versions without quotes are more
complex, for they may transform the value in various ways.
Additionally, unless ksh_arrays is set (it's unset by default), these
two are equivalent:
"${array[@]}"
"${(@)array}"
And these four are equivalent:
${array[@]}
${(@)array}
${array}
$array
Roman.
next prev parent reply other threads:[~2022-11-17 9:00 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-10 0:43 coloring substitution seems to eat next line Ray Andrews
2022-11-10 8:02 ` Roman Perepelitsa
2022-11-10 18:25 ` Ray Andrews
2022-11-10 18:36 ` Roman Perepelitsa
2022-11-10 18:45 ` Ray Andrews
2022-11-10 18:54 ` Bart Schaefer
2022-11-10 19:28 ` Ray Andrews
2022-11-10 20:22 ` Bart Schaefer
2022-11-10 21:42 ` Ray Andrews
2022-11-10 21:51 ` Roman Perepelitsa
2022-11-11 17:24 ` Ray Andrews
2022-11-10 22:47 ` Bart Schaefer
2022-11-10 23:07 ` Ray Andrews
2022-11-10 23:27 ` Bart Schaefer
2022-11-11 15:00 ` Ray Andrews
2022-11-11 18:15 ` Bart Schaefer
2022-11-11 18:50 ` Ray Andrews
2022-11-11 19:25 ` Bart Schaefer
2022-11-11 21:26 ` Ray Andrews
2022-11-12 4:24 ` Bart Schaefer
2022-11-12 14:03 ` Ray Andrews
2022-11-13 15:09 ` Ray Andrews
2022-11-14 14:12 ` Roman Perepelitsa
2022-11-14 17:08 ` Ray Andrews
2022-11-14 17:12 ` Roman Perepelitsa
2022-11-14 18:58 ` Ray Andrews
2022-11-14 20:00 ` Bart Schaefer
2022-11-14 23:25 ` Ray Andrews
2022-11-15 14:17 ` Belaboring substitution syntax Ray Andrews
2022-11-16 1:49 ` Bart Schaefer
2022-11-16 2:54 ` Ray Andrews
2022-11-16 6:26 ` Bart Schaefer
2022-11-16 14:08 ` Ray Andrews
2022-11-16 14:13 ` Roman Perepelitsa
2022-11-17 2:31 ` Bart Schaefer
2022-11-17 8:59 ` Roman Perepelitsa [this message]
2022-11-17 16:02 ` Ray Andrews
2022-11-16 20:46 ` Ray Andrews
2022-11-16 10:32 ` Roman Perepelitsa
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