From: Stephane Chazelas <stephane@chazelas.org>
To: Bart Schaefer <schaefer@brasslantern.com>
Cc: Zsh hackers list <zsh-workers@zsh.org>
Subject: Re: [PATCH] (take two?) typeset array[position=index]=value / unset hash[$stuff]
Date: Wed, 2 Jun 2021 17:02:06 +0100 [thread overview]
Message-ID: <20210602160206.jhfp4lvua2hvub7c@chazelas.org> (raw)
In-Reply-To: <CAH+w=7aCikLxobxVR9g7Cp3S_LxyY_1hm0LHU8-M0QGSj2JNfA@mail.gmail.com>
2021-06-02 07:52:25 -0700, Bart Schaefer:
[...]
> > I have to admit I don't see the problem here. I would have
> > thought allowing a[]=foo and unset 'a[]' would be no-brainers
>
> Mostly I was thinking about
>
> key=$(some derived value)
> unset "hash[$key]"
>
> In existing code that would fail on [[ -z $key ]], but you can't see
> that by examination.
Not sure I follow. That script doesn't work properly atm as it
fails to unset the corresponding hash element and would be fixed
once we allow unset 'hash[]'
I can't think of real life scenarios where one would *rely* on
unset 'hash[]'
Aborting the shell with a
zsh:unset:1: hash[]: invalid parameter name
error.
> > as there's no concern about backward compatibility as those
> > currently return an error.
>
> That's not our usual criteria for backward compatibility. Usually we
> only change things if the new construct was previously a syntax error,
> something that would prevent an old script from even being properly
> parsed.
By that logic, we could never add features like new options to
builtins or new flags. For instance, we couldn't add a -k option
to unset because
unset -k key arr
currently is not a zsh syntax error, that script is parsed OK,
and that command returns with:
unset: bad option: -k
[...]
> > Even for plain arrays, IMO, it would make sense to allow empty
> > subscripts. In most contexts, an empty arithmetic expression is
> > interpreted as 0:
>
> But ... there's no such thing as array position 0 in native zsh.
But it would make the API more consistent if array subscripts
could be any arithmetic expressions or comma-separated pair of
arithmetic expressions.
And when ksharrays is not enabled a[] to return the same error
as for a[0] or a[empty] ("assignment to invalid subscript
range").
Note that 0 position is allowed in second place:
a[2,0]=x
for instance (or a[2,empty]=x, but not a[2,]=x atm) to insert a
x in second position.
I'm not saying that's something we should do or would be
terribly useful, just that it would make the interface more
consistent, and that array[] being rejected should not be a
justification for rejecting assoc[].
[...]
> > The fact that (e) is recognised and (ee) is
> > not also makes for a not very consistent API.
>
> What would (ee) mean?
The e flag passed twice.
echo $a[(e)*], $a[(ee)*], $a[(eee)*]
All expand to element of key "*".
--
Stephane
next prev parent reply other threads:[~2021-06-02 16:02 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-16 21:10 regexp-replace and ^, word boundary or look-behind operators Stephane Chazelas
2019-12-16 21:27 ` Stephane Chazelas
2019-12-17 7:38 ` Stephane Chazelas
2019-12-17 11:11 ` [PATCH] " Stephane Chazelas
2019-12-18 0:22 ` Daniel Shahaf
2019-12-18 8:31 ` Stephane Chazelas
2020-01-01 14:03 ` [PATCH v2] " Stephane Chazelas
2021-04-30 6:11 ` Stephane Chazelas
2021-04-30 23:13 ` Bart Schaefer
2021-05-05 11:45 ` [PATCH v3] regexp-replace and ^, word boundary or look-behind operators (and more) Stephane Chazelas
2021-05-31 0:58 ` Lawrence Velázquez
2021-05-31 18:18 ` Bart Schaefer
2021-05-31 21:37 ` [PATCH] (?) typeset array[position=index]=value Bart Schaefer
2021-06-01 5:32 ` Stephane Chazelas
2021-06-01 16:05 ` Bart Schaefer
2021-06-02 2:51 ` [PATCH] (take two?) typeset array[position=index]=value / unset hash[$stuff] Bart Schaefer
2021-06-02 10:06 ` Stephane Chazelas
2021-06-02 14:52 ` Bart Schaefer
2021-06-02 16:02 ` Stephane Chazelas [this message]
2021-06-02 9:11 ` [PATCH] (?) typeset array[position=index]=value Stephane Chazelas
2021-06-02 13:34 ` Daniel Shahaf
2021-06-02 14:20 ` Stephane Chazelas
2021-06-02 15:59 ` Bart Schaefer
2021-06-03 2:04 ` [PATCH (not final)] (take three?) unset "array[$anything]" Bart Schaefer
2021-06-03 2:42 ` Bart Schaefer
2021-06-03 6:12 ` Bart Schaefer
2021-06-03 8:54 ` Peter Stephenson
2021-06-03 13:13 ` Stephane Chazelas
2021-06-03 14:41 ` Peter Stephenson
2021-06-04 19:25 ` Bart Schaefer
2021-06-05 18:18 ` Peter Stephenson
2021-06-09 23:31 ` Bart Schaefer
2021-06-13 16:51 ` Peter Stephenson
2021-06-13 18:04 ` Bart Schaefer
2021-06-13 19:48 ` Peter Stephenson
2021-06-13 21:44 ` Bart Schaefer
2021-06-14 7:19 ` Stephane Chazelas
2021-06-03 18:12 ` Bart Schaefer
2021-06-04 8:02 ` Stephane Chazelas
2021-06-04 18:36 ` Bart Schaefer
2021-06-04 20:21 ` Stephane Chazelas
2021-06-05 0:20 ` Bart Schaefer
2021-06-05 17:05 ` Stephane Chazelas
2021-06-10 0:14 ` Square brackets in command position Bart Schaefer
2021-06-03 6:05 ` [PATCH (not final)] (take three?) unset "array[$anything]" Stephane Chazelas
2021-06-03 6:43 ` Bart Schaefer
2021-06-03 7:31 ` Stephane Chazelas
2021-06-10 0:21 ` [PATCH] (?) typeset array[position=index]=value Bart Schaefer
2021-06-05 4:29 ` Mikael Magnusson
2021-06-05 5:49 ` Bart Schaefer
2021-06-05 11:06 ` Mikael Magnusson
2021-06-05 16:22 ` Bart Schaefer
2021-06-18 10:53 ` Mikael Magnusson
2024-03-08 15:30 ` [PATCH v3] regexp-replace and ^, word boundary or look-behind operators (and more) Stephane Chazelas
2024-03-09 8:41 ` [PATCH v5] " Stephane Chazelas
2024-03-09 9:21 ` MBEGIN when =~ finds bytes inside characters (Was: [PATCH v5] regexp-replace and ^, word boundary or look-behind operators (and more).) Stephane Chazelas
2024-03-09 13:03 ` [PATCH v3] regexp-replace and ^, word boundary or look-behind operators (and more) Stephane Chazelas
2024-03-10 19:52 ` [PATCH v6] " Stephane Chazelas
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