From: Pascal Bourguignon <pjb@informatimago.com>
Subject: forward-sexp and quote
Date: 20 Jan 2003 02:52:32 +0100 [thread overview]
Message-ID: <87k7h0fuzj.fsf@thalassa.informatimago.com> (raw)
(forward-sexp 1) eats quotes and backquotes, but (forward-sexp -1) doesn't.
That is, when there are spaces after the quote.
Which is unfortunate because the reader doesn't mind these spaces
and reads correctly the quoted expression:
.' (a b c) --(forward-sexp 1)--> ' (a b c). --(forward-sexp -1)--> ' .(a b c)
;; dot showing the point.
(show ' ( a b c))
==> (a b c)
The bug can be traced to scan-sexp which is a built-in.
(show (version))
==> "GNU Emacs 21.2.1 (i686-pc-linux-gnu, X toolkit)
of 2002-10-26 on thalassa"
(progn
(find-file "*bug*")
(emacs-lisp-mode)
(erase-buffer)
(mapc (lambda (s)
(let (before after end read-before read-after)
(goto-char (point-max))
(insert "\n")
(setq before (point))
(insert s)
(setq end (point))
(goto-char before)
(setq read-before (read-from-string (buffer-substring (point) end)))
(forward-sexp 1)
(forward-sexp -1)
(setq after (point))
(setq read-after (read-from-string (buffer-substring (point) end)))
(goto-char (point-max))
(insert (format "\nread before: %S\n" read-before))
(insert (format "read after : %S\n" read-after))
(insert (format "before=%S\nafter =%S %s\n\n" before after
(if (= before after) "" "BUG!")))))
'("' (a b c)" "'(a b c)" "' abc" "'abc")))
' (a b c)
read before: ((quote (a b c)) . 9)
read after : ((a b c) . 7)
before=2
after =4 BUG!
'(a b c)
read before: ((quote (a b c)) . 8)
read after : ((quote (a b c)) . 8)
before=101
after =101
' abc
read before: ((quote abc) . 5)
read after : (abc . 3)
before=207
after =209 BUG!
'abc
read before: ((quote abc) . 4)
read after : ((quote abc) . 4)
before=298
after =298
--
__Pascal_Bourguignon__ http://www.informatimago.com/
----------------------------------------------------------------------
There is a fault in reality. Do not adjust your minds. -- Salman Rushdie
next reply other threads:[~2003-01-20 1:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-01-20 1:52 Pascal Bourguignon [this message]
-- strict thread matches above, loose matches on Subject: below --
2003-01-20 1:33 forward-sexp and quote Pascal Bourguignon
2003-01-21 18:17 ` Richard Stallman
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=87k7h0fuzj.fsf@thalassa.informatimago.com \
--to=pjb@informatimago.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.