From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Michael Heerdegen <michael_heerdegen@web.de>
Cc: ndame <emacsuser@freemail.hu>,
"emacs-devel@gnu.org" <emacs-devel@gnu.org>
Subject: Re: Shouldn't emacs print long lists with newlines?
Date: Wed, 07 Aug 2019 06:51:25 -0400 [thread overview]
Message-ID: <jwva7clfekv.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <87muglxxns.fsf@web.de> (Michael Heerdegen's message of "Wed, 07 Aug 2019 09:05:59 +0200")
>> Shouldn't the printing code be smarter and print long lists with
>> newlines, every item in a separate line, to avoid the long line
>> issue?
[ My minibuffer is exactly 1-line tall (and it's a separate frame, so
Emacs is not allowed to grow it), so spreading the output on several
lines is not always a good solution. ]
> If it should depends on the use case. It should be able to do so when
> the user wants that - especially pretty printing (pp). So far this has
> been discussed here and there, but so far nobody has implemented it.
I don't think Edebug tries to pretty print this, currently.
But if we want to improve the pretty printer to fold such "parenthesis
deserts", we can try a patch like the one below,
Stefan
diff --git a/lisp/emacs-lisp/pp.el b/lisp/emacs-lisp/pp.el
index de4cbfc0e1..21de326421 100644
--- a/lisp/emacs-lisp/pp.el
+++ b/lisp/emacs-lisp/pp.el
@@ -50,6 +50,33 @@ pp-to-string
(pp-buffer)
(buffer-string)))
+(defun pp--long-line ()
+ "Cut the line before point and before `fill-column' if needed."
+ ;; FIXME: This still leaves lines longer than fill-column because
+ ;; When pp-buffer calls us, the text is flush-left rather than
+ ;; properly indented, so (current-column) is not the real column at
+ ;; which the text will end up.
+ (let ((end (point)))
+ (when (> (current-column) fill-column)
+ (forward-line 0)
+ (let ((last nil))
+ (while (progn
+ (skip-syntax-forward "^\"< \\")
+ (skip-syntax-forward " ")
+ (and (< (point) end)
+ (or (< (current-column) fill-column)
+ (null last))))
+ (setq last (point))
+ (pcase (char-syntax (char-after))
+ (?\\ (forward-char 2))
+ (?\" (forward-sexp 1))
+ (?\< (end-of-line))))
+ (when last
+ (goto-char last)
+ (skip-syntax-backward " ")
+ (delete-region (point) last)
+ (insert "\n"))))))
+
;;;###autoload
(defun pp-buffer ()
"Prettify the current buffer with printed representation of a Lisp object."
@@ -58,6 +85,7 @@ pp-buffer
;; (message "%06d" (- (point-max) (point)))
(cond
((ignore-errors (down-list 1) t)
+ (pp--long-line)
(save-excursion
(backward-char 1)
(skip-chars-backward "'`#^")
@@ -67,6 +95,7 @@ pp-buffer
(progn (skip-chars-backward " \t\n") (point)))
(insert "\n"))))
((ignore-errors (up-list 1) t)
+ (pp--long-line)
(skip-syntax-forward ")")
(delete-region
(point)
next prev parent reply other threads:[~2019-08-07 10:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-05 20:05 Shouldn't emacs print long lists with newlines? ndame
2019-08-07 7:05 ` Michael Heerdegen
2019-08-07 10:51 ` Stefan Monnier [this message]
2019-08-07 12:04 ` martin rudalics
2019-08-28 17:23 ` Stefan Monnier
2019-08-29 7:46 ` martin rudalics
2019-08-07 12:43 ` ndame
2019-08-07 14:28 ` Michael Heerdegen
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