From: Bart Schaefer <schaefer@brasslantern.com>
To: Zsh hackers list <zsh-workers@zsh.org>
Subject: Re: Up-scope named references, vs. ksh
Date: Wed, 28 Feb 2024 21:16:13 -0800 [thread overview]
Message-ID: <CAH+w=7aGtWkXFYXQRnL808CscE0=CsAvA3zpoUK6LcSzk5JEww@mail.gmail.com> (raw)
In-Reply-To: <20240221201215.anpjcfav6na55gg6@chazelas.org>
Lost track of this for a bit ..
On Wed, Feb 21, 2024 at 12:12 PM Stephane Chazelas
<stephane@chazelas.org> wrote:
>
> Like:
> - if var is found (declared) in the current scope, record that
> it's that of that scope that it is to get the value of or set
> or unset (and reset again thereafter)
> - if not, repeat for parent scope
> - if not found at all, record that it's to be at the global
> scope.
That's where this whole discussion started: It's not good enough to
"record that it's to be global" because if a local of the same name is
later declared, there is no way to insert a new global "above" that,
it's akin to attempting to allocate new space in your caller's stack
frame in C (except there's one stack for each parameter name). The
workaround in shell code is to start with "typeset -g a" (using your
example code) to initialize the top stack frame. The workaround in
underlying C code would be to have "typeset -n r1=a" (again your
example) implicitly create the global $a as early as possible.
> f() { typeset a; unset a; g; echo "$a"; }
> g() { h; }
> h() {
> typeset b=x
> typeset -n r1=a r2=b r3=c
> typeset a=foo c=bar
> r1=x r2=y r3=z
> unset r{1..3}
> r1=x r2=y r3=z
> }
> f
>
> r1=x sets the $a of f, r2=y sets the $b of h, and r3=z sets a
> global $c both times.
It works that way for "the $a of f" and "the $b of h", but r3 assigns
"the $c of h" both times. Change that to:
h() {
typeset b=x
typeset -n r1=a r2=b r3=c
typeset a=foo
r1=x r2=y r3=z
typeset c=bar
unset r{1..3}
r1=x r2=y r3=z
}
And now the first r3=z creates the global $c so the second r3=z
continues to refer to it.
next prev parent reply other threads:[~2024-02-29 5:16 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-06 2:21 [PATCH 1/3]: Add named references Bart Schaefer
2023-02-08 3:45 ` Oliver Kiddle
2023-02-08 4:59 ` Bart Schaefer
2023-02-08 23:16 ` Bart Schaefer
2023-02-09 0:47 ` Oliver Kiddle
2023-02-09 2:01 ` Oliver Kiddle
2023-02-09 5:45 ` Bart Schaefer
2023-02-09 4:49 ` Bart Schaefer
2023-02-09 20:49 ` Oliver Kiddle
2023-02-09 23:07 ` Bart Schaefer
2023-02-11 3:04 ` Bart Schaefer
2023-02-11 3:55 ` Bart Schaefer
2023-02-11 5:36 ` Speaking of dangerous referents Bart Schaefer
2023-02-12 8:00 ` Oliver Kiddle
2023-02-12 8:34 ` Bart Schaefer
2023-02-11 7:02 ` [PATCH 1/3]: Add named references Oliver Kiddle
2023-02-11 7:45 ` Bart Schaefer
2023-02-11 23:43 ` Bart Schaefer
2023-02-11 23:45 ` Bart Schaefer
2023-02-12 7:38 ` Oliver Kiddle
2024-02-11 7:00 ` Stephane Chazelas
2024-02-11 16:14 ` Bart Schaefer
2024-02-11 16:42 ` Bart Schaefer
2024-02-18 3:26 ` Up-scope named references, vs. ksh Bart Schaefer
2024-02-20 21:05 ` Stephane Chazelas
2024-02-20 22:30 ` Bart Schaefer
2024-02-21 20:12 ` Stephane Chazelas
2024-02-29 5:16 ` Bart Schaefer [this message]
2024-03-01 18:22 ` Stephane Chazelas
2024-03-01 20:34 ` Bart Schaefer
2024-03-02 7:29 ` Bart Schaefer
2024-03-02 23:55 ` [PATCH] "typeset -nu" (was Re: Up-scope named references, vs. ksh) Bart Schaefer
2024-03-01 23:28 ` Up-scope named references, vs. ksh Bart Schaefer
2024-03-03 13:44 ` Stephane Chazelas
2024-03-03 19:04 ` Bart Schaefer
2024-03-03 20:27 ` Stephane Chazelas
2024-03-03 22:58 ` Bart Schaefer
2024-03-04 19:59 ` Stephane Chazelas
2024-03-05 1:05 ` Oliver Kiddle
2024-03-05 2:53 ` Bart Schaefer
2024-03-05 5:43 ` Mikael Magnusson
2024-03-05 6:30 ` Stephane Chazelas
2024-03-06 5:04 ` [PATCH] local vs. nameref scoping (was Re: Up-scope named references, vs. ksh) Bart Schaefer
2023-02-12 9:02 ` [PATCH 1/3]: Add named references Oliver Kiddle
2023-02-12 18:59 ` Bart Schaefer
2023-02-12 19:45 ` PM_* flags in zsh.h (was Re: [PATCH 1/3]: Add named references) Bart Schaefer
2023-02-12 21:01 ` Oliver Kiddle
2023-02-12 22:54 ` [PATCH 1/3]: Add named references Oliver Kiddle
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAH+w=7aGtWkXFYXQRnL808CscE0=CsAvA3zpoUK6LcSzk5JEww@mail.gmail.com' \
--to=schaefer@brasslantern.com \
--cc=zsh-workers@zsh.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/zsh/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).