Re: [Emacs-diffs] master 9ce1d38: Use curved quotes in core elisp diagnostics

[Paul Eggert <eggert@cs.ucla.edu>]

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>
>    > Here's what's implemented in master now (either works):
>
>    >    (format "‘add-to-list’ can't use var ‘%s’; use ‘push’ or ‘cl-pushnew’" sym)
>
> That's not a feature -- it is just a way you can use the old 'format'
> function.

The feature has been removed in master due to compatibility concerns, so this 
part of the discussion is moot now.  However, the idea was that ‘format’ 
requoted as per user preference, so that the resulting string would look like this:

    "`add-to-list' can't use var `foo'; use `push' or `cl-pushnew'"

if SYM was "foo" and the user preferred the grave quoting style.

I'm working on a patch to do this sort of requoting in a separate new function, 
which should resolve the compatibility concerns.

>    >    (format "%q can't use var %qs; use %qs or %qs" "add-to-list" sym "push"
>    > "cl-pushnew")
>
> what is the difference between %q and %qs?

Sorry, the first %q was a typo; it should have been %qs.

>    > Digraphs were proposed, but not implemented:
>
>    >    (format "%<add-to-list%> can't use var %<%s%>; use %<push%> or
>    > %<cl-pushnew%>" sym)
>
> That seems much cleaner, since it does not require moving fixed parts
> of the message out of the format string.
>
> Does anyone have an objection to this feature?

Yes, it's ugly and hard to read and maintain.  It's reminsicent of the trigraphs 
of ANSI C (and it's being introduced for the same reasons!) and in the long run 
it would suffer the same fate as trigraphs.

It's simpler when one can cut and paste text from text files into Lisp strings 
and vice versa, and have it just work.  Requiring escapes like %< and %> would 
work against this simplicity.  Obviously we can't always cut and paste arbitrary 
text, but we should be able to do so with single quotes without having to resort 
to a trigraph-like syntax.