From: "João Távora" <joaotavora@gmail.com>
To: Drew Adams <drew.adams@oracle.com>
Cc: 33998@debbugs.gnu.org, Deus Max <deusmax@gmx.com>
Subject: bug#33998: 27.0.50; cl-delete does not delete the first list element
Date: Tue, 8 Jan 2019 18:57:12 +0000 [thread overview]
Message-ID: <CALDnm53KOymAEghHTYNvNnDo231Na4AV9LpLtD6g6CY+EYwonA@mail.gmail.com> (raw)
In-Reply-To: <ddf9ca15-606b-4bcc-a100-92465d9d9ec5@default>
On Tue, Jan 8, 2019 at 6:46 PM Drew Adams <drew.adams@oracle.com> wrote:
>
> > > Again, you should set the variable to the value
> > > returned by `cl-delete' only if that's what you
> > > want
> >
> > OK. Say you don't. Say you don't SETQ the variable
> > to the return value. What do you expect to be left
> > with in the value bound to the SEQ symbol?
> >
> > > Pretty simple, really.
> >
> > Then answer the pretty simple question above.
>
> Without setting variable `seq' (i.e., without
> the `setq'), that variable is still bound to
> whatever it was bound to prior to your invoking
> `(cl-delete thing seq)'. Presumably it was
> bound to a cons.
It could have been bound to a vector. cl-delete (as delq, delete)
accepts sequences. And contrary to those two, it makes
no guarantees as to how it potentially destroys the original
sequence. So unless you're relying on a particular
implementation, relying on SEQ after calling cl-delete on it
is a bad, bad idea.
So yes, always (setq SEQ (cl-delete THING SEQ)). With
the extraordinary exception that you're leaving the scope
where SEQ is visible. Then you can bypass it.
João
next prev parent reply other threads:[~2019-01-08 18:57 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-06 13:30 bug#33998: 27.0.50; cl-delete does not delete the first list element Deus Max
2019-01-07 17:13 ` João Távora
2019-01-07 17:28 ` Drew Adams
2019-01-07 18:04 ` João Távora
2019-01-07 18:14 ` Drew Adams
2019-01-08 13:45 ` João Távora
2019-01-08 18:22 ` Drew Adams
2019-01-08 18:31 ` João Távora
2019-01-08 18:45 ` Drew Adams
2019-01-08 18:57 ` João Távora [this message]
2019-01-08 19:07 ` Drew Adams
2019-01-08 21:38 ` João Távora
2019-01-09 1:30 ` Drew Adams
2019-01-07 20:20 ` Deus Max
2019-01-07 20:27 ` Dmitry Gutov
2019-01-07 20:48 ` Deus Max
2019-01-07 21:06 ` João Távora
2019-01-07 22:46 ` Deus Max
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=CALDnm53KOymAEghHTYNvNnDo231Na4AV9LpLtD6g6CY+EYwonA@mail.gmail.com \
--to=joaotavora@gmail.com \
--cc=33998@debbugs.gnu.org \
--cc=deusmax@gmx.com \
--cc=drew.adams@oracle.com \
/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 external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.