From: Stephane Chazelas <stephane@chazelas.org>
To: Mikael Magnusson <mikachu@gmail.com>
Cc: zsh-workers@zsh.org
Subject: Re: RFC PATCH: Sketch at :@ subscripting
Date: Sat, 19 Dec 2020 09:13:14 +0000 [thread overview]
Message-ID: <20201219091314.dxslsscyiqffa3il@chazelas.org> (raw)
In-Reply-To: <20201218131815.25999-1-mikachu@gmail.com>
2020-12-18 14:18:15 +0100, Mikael Magnusson:
[...]
> The idea is that you can do this:
> % typeset -a somearray=( 'data here' 'some words' etc etc 1 2 3 4 ) idx=(1 3 5)
> % echo ${somearray:@idx}
> data here etc 1
[...]
Hi Mikael,
I can't help but think that allowing to specify the indexes
directly as perl does for instance in:
print @list[1, 4, 2, 7..10, @idx, -1];
And in assignments as well:
@list[@idx] = qw(new values here);
would be more useful.
It's unfortunate that "," is used for ranges in $a[1,3] in zsh
especially considering that "," is also an arithmetic operator
(btw:
$ a=({a..z})
$ echo ${a[1,3]}
a b c
$ i=1,3
$ echo ${a[i]}
c
$ echo ${a[$i]}
a
??) and that {1,3,{5..7}} otherwise follows the perl semantics
(and extends it as it allows backward ranges).
${list[2 6 8]} in zsh wouldn't work as ${list[2 -1]} already
means something different, but maybe ${list[2;6,9;${(j[;])idx},-1]}
would?
That would mean no backward range as $a[3,1] ATM is the empty
list but backward sets would still be possible with $a[3;2;1].
Maybe another option could be $a[{1,4,{8..2},$^idx}] so as to
reuse an already known syntax?
Except that:
$ i=(a b)
$ echo {1,2,$^i}.
1. 2. a. 1. 2. b.
$ echo {1,2,{a,b}}.
1. 2. a. b.
Syntax would also have to be restricted to a[{...}], no
a[{1,2}0] for instance.
a[{${(f)^"$(shuf -n 5 -i 1-100)"}]=({a..e})
soon becomes awkward as well.
There's also the question of
a[1;5]=(a b c)
a[1;5]=(a)
...
Having a syntax that could also apply to associative arrays
would be best.
--
Stephane
next prev parent reply other threads:[~2020-12-19 9:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-18 13:18 Mikael Magnusson
2020-12-19 9:13 ` Stephane Chazelas [this message]
2021-03-27 20:27 ` Bart Schaefer
2021-04-03 19:48 ` Lawrence Velázquez
2021-04-04 17:30 ` Daniel Shahaf
2021-04-10 20:38 ` Lawrence Velázquez
2021-04-10 21:59 ` Bart Schaefer
2021-04-13 11:54 ` Daniel Shahaf
2021-04-13 21:25 ` Bart Schaefer
2021-03-27 19:41 ` Lawrence Velázquez
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