Re: [Emacs-diffs] master c4151eb: Improve the optional translation of quotes

[Dmitry Gutov <dgutov@yandex.ru>]

On 06/25/2015 05:05 PM, Paul Eggert wrote:

> I didn't see any patch in that email, unfortunately -- perhaps you
> forgot to include it?

Sorry, it's attached now.

> True.  But it's still a temptation we should strive to avoid.

Depends on what we call complicated. Like Richard mentioned, at least we 
can try to leave unpaired quotes alone. Or not, I don't really care that 
much personally.

>> - Like you said: "describe-variable should curve the quotes in the doc
>> string,
>> but not in the contents of the variable". The code that prints the
>> value will
>> need to add some text property to it ("verbatim"?
>> "font-lock-ignore"?), and the
>> font-lock rule can look it up and skip those regions. Nothing too hard.
>
> As you'll recall, I don't understand font-lock.

There's no requirement for you to implement all of it yourself. You can 
take my patch, look for problems, and ask for them to be fixed.

You'll have to do the substitute-command-keys part, though.

> That being said, I
> worry that all this stuff would be complicated and would involve using
> undocumented or poorly-documented features (see Bug#20613).

I've enumerated practical considerations of having it implemented *not* 
in font-lock. If some font-lock features lack documentation, demand it 
to be added, then.

> Also, it's not clear how the overall approach would work on limited
> displays that don't have alternate fonts and/or colors.  Suppose, for
> example, that the user is running 'emacs --color=never' on a character
> terminal?

diff --git a/lisp/help-mode.el b/lisp/help-mode.el
index f99e916..6256513 100644
--- a/lisp/help-mode.el
+++ b/lisp/help-mode.el
@@ -287,6 +287,13 @@ Commands:
  \\{help-mode-map}"
    (set (make-local-variable 'revert-buffer-function)
         'help-mode-revert-buffer)
+  (setq font-lock-defaults '(nil t))
+  (font-lock-add-keywords
+   nil '(("`\\([^[:space:]'`‘’][^'`‘’]*\\)?'"
+	  . (0 (progn (compose-region (match-beginning 0)
+				      (1+ (match-beginning 0)) ?‘)
+		      (compose-region (1- (match-end 0)) (match-end 0) ?’)
+		      nil)))))
    (set (make-local-variable 'bookmark-make-record-function)
         'help-bookmark-make-record))