Re: A simple solution to "Upcoming loss of usability ..."

[Dmitry Gutov]

On 06/27/2015 08:28 PM, Paul Eggert wrote:

> In that case I don't understand the patch being against f743819.
> f743819 already has some curved quotes in docstrings, to avoid
> ambiguities of using grave accent and apostrophe to quote.  So that
> patch against f743819 won't determine whether font-lock can address this
> issue without using curved quotes in docstrings.

I just needed a version where substitute-command-keys doesn't replace 
the quotes (so that the font-lock rules do have something to work on). 
The question of ambiguity is a matter of refining the patch.

> Even with this in mind, though, the patch mishandles some quotes.  For
> example, the docstring for texinfo-format-verb contains:
>
>    For example, @verb\{|@|\} results in @ and
>    @verb\{+@'e?`!`+} results in @'e?`!`.
>
> The patch displays this as:
>
>    For example, @verb{|@|} results in @ and
>    @verb{+@'e?`!‘+} results in @’e?`!`.
>
> which is incorrect: those curved quotes should be grave accent and
> apostrophe.

Only because the regexp is constructed this way, and we haven't picked 
an escaping syntax.

> It'd be impractical to work around this sort of problem entirely with
> clever font-lock regular expressions.  We will need some escape syntax
> to suppress transliteration for exceptional docstrings like the above.
> I think you've mentioned the need for that sort of thing, but it's not
> clear what it would look like or

I've described the possible options in the previous message here of this 
subthread (in the second half):

http://lists.gnu.org/archive/html/emacs-devel/2015-06/msg00592.html

So, do you find "\\" acceptable? Should I send a patch with support for it?

> how it would be implemented with font-lock.

There are several examples in our Lisp code of searching for only 
unescaped instances of some character, using a regexp. But failing that, 
examining characters preceding a match would work almost as well.

> Plus, as we've mentioned, the patch can mishandle user-supplied values
> that contain grave accent and apostrophe.

Nothing surprising there either. I'll try to handle it in the next 
version of the patch.

> > It will be very easy to limit the conversion to only within strings.
>
> As I understand it we gave up on transliteration of Elisp source code
> after you wrote the above, so for now I'll not comment on this point (or
> the other points of the message that talk about transliterating source
> code).

You have also snipped the suggestions about the escaping syntax.

> > Is Info actually relevant in this discussion? Looking at info.el, it
> > seems to
>
> It's relevant, as it uses and displays the curved quotes that some users
> find objectionable, and did so even in 24.5.

I thought the external program performs the conversion. But yes, 
converting those curly quotes to straight ones in font-lock is also 
possible.