bug#20707: [PROPOSED PATCH] Use curved quoting in C-generated errors

[Alan Mackenzie]

Hello, Paul.

On Thu, Jun 11, 2015 at 07:41:54PM -0700, Paul Eggert wrote:
> Alan Mackenzie wrote:

> > My setup couldn't display curly single quotes

> Sure it could.  It displayed curved single quotes as curved single quotes.  
> Your 
> objection was that your setup also displayed grave accent and apostrophe as 
> curved single quotes (a style you happen to prefer), ....

No.  The curly quotes had hijacked the glyphs for 0x27 and 0x60.  I think
it likely that these glyphs originated as those for 0x27 and 0x60, and
were so before Unicode even existed.

> ... and you wanted your setup to display *different-shaped curves* for
> curved single quotes.  This will not be not a problem to the few
> ordinary Emacs users who happen to use a similar obsolescent
> environment; they'll merely see nicely curved single quotes and move
> on.

That's pure speculation.  So far, we've got one data point, me, and I was
not at all happy about this aliasing when I discovered it.  Nobody has
yet chimed in and said they'd be happy about it on their own system.

> > none of them that I've seen so far have distinct glyphs for the curly
> > quotes.

> Again, distinct glyphs are not a requirement for ordinary Emacs users.

Again, we just don't know this one way or the other.  Anyway I thought
we'd agreed on the WYSIWYG principle.  With this aliasing, WYS is
ambiguous, WYG is not.

> That being said, for Emacs developers such as yourself, the
> Lat15-Terminus16 font I mentioned earlier has distinct glyphs for
> curved quotes, as does Lat15-TerminusBold16.  You can find them
> archived at <http://bugs.gnu.org/20707>.  There are many other choices
> in this area.

Yes, but of the standard fonts (i.e., those distributed in the kbd
GNU/Linux package) I'm not sure there're any with distinct glyphs for
curly quotes.  I think whatever happens, messing around with fonts would
be needed for lots of console users.

> > That easiness remains controversial.

> It's certainly easier to read text quoted ‘like this’ than to read text 
> quoted 
> \`like this\'.

Yes, but marginally so.  It's not easier to type it, electric-quote-mode
notwithstanding.  Nobody's ever complained about \"like this\" in a
string.  We all cope with far worse in complicated regular expressions.

> > To be useful, it would have to become the standard way of quoting
> > symbols.

> I doubt whether it'll be the standard.  It's uglier and more complicated than 
> the alternative.  Its main advantage is that it's easier to type for users 
> who 
> want to type only ASCII.

The main advantage is that it would allow users to chose whether they want
curly quotes routinely in their doc strings.

How about another approach - leave the doc strings as they are, and
translate `foo-bar' to ?foo-bar? when doing C-h f/v, and so on?  `..' is
used in doc strings mainly for quoting _symbols_, and it may well be that
that's the only use of this quoting style.  Making this enhancement would
certainly be less work than changing several tens of thousands of
`foo-bar's in the source code.

> > Where do you see any portability hassles?

> Code might work when running on a typical Emacs system, but might fail on an 
> Emacs system configured --without-curved-quotes, because Emacs will generate 
> different strings that will be treated differently.

I can't see that.  There'd just be displayable characters in the two
versions - why would it matter that they were different?  Maybe if the
string were being passed to `read', there could be a difference, but in
that case it's the curly-quote version which is more likely to be
erroneous.

> > What exactly do you mean by "display problems fixed"?

> On the rare systems that don't display curved quotes as quotes, Emacs should 
> display straight quotes as substitutes.  That's good enough for these rare 
> and 
> obsolescent systems.

OK.  I don't agree with this approach, of course.

> > I don't think it's TRT simply to curlify any quote typed within a string

> Electric Quote mode doesn't do that.  If you type an apostrophe, it normally 
> leaves the apostrophe alone.  And in the rare cases where one really wants a 
> grave accent and not a left single quote, it's easy enough to type C-q `.

OK.  I hadn't tried typing just apostrophes.  Sorry.

[ .... ]

-- 
Alan Mackenzie (Nuremberg, Germany).