RE: Single quotes in Info

[Drew Adams]

> > > I'm not at all sure we should compare a and á equal.  It's an
> > > additional feature anyway.
> >
> > I get the impression that you are talking only about a built-in
> > (more or less hard-coded, predefined) set of equivalence classes
> > of chars, whatever that set might be defined as.
> 
> We certainly should have predefined equivalence support based on the
> Unicode Standard's recommendations.  That is the state of the art
> these days, and any respectable text editor should include such
> support.
> 
> > Is that right, or would users be able to define the equivalence
> > classes you are thinking of?
> 
> We should first provide users with a set of sensible optional
> behaviors that they are likely to expect in various situations.  Each
> option will invoke a certain predefined behavior, such as whether or
> not equivalence classes are at all considered, whether or not a and á
> compare equal, etc.  There are important use cases for each one of
> those, exactly like there important use cases for both case-sensitive
> and case-insensitive search.
> 
> Once we have that in place, we can add user-defined additions.  I
> expect them to be relatively minor and mostly mode-specific, such as
> the special treatment of quotes and other special characters in Info
> buffers.  Why minor? because Unicode already thought out and defined
> almost any imaginable feature in this regard, so chances that some
> user might need something in addition are small.
> 
> Mode-specific additions could be just alists that map characters or
> strings to their equivalents.  Since I don't expect those to become
> large, there's no need for anything fancier, IMO.

Glad to see all of those specific replies.  It all sounds good to me,
including the proposed development priorities.

> > If they would not then a separate but desirable (IMO) feature
> > would be for users to be able to easily define their own such
> > equivalence classes.
> 
> I wouldn't call them equivalence classes.  Users are not expected to
> be experts in Unicode features, its various data tables, and their
> implementation in Emacs.  We should instead provide easy-to-customize
> option variables to select out of an array of predefined features
> based on Unicode tables we already have.  User additions should be
> some simple data structure that don't require any special expertise.

I don't care what you call them.  In the interest of brevity I also
did not explicitly mention the possibility of associating multiple-char
sequences with other such or with single chars (e.g., associating "=>"
with ⇒ or "ss" with ß, though those two would presumably be predefined).

To me, each set of such associations constitutes an equivalence class,
but I don't care what nomenclature is used to describe it, as long
as it is clear.

My point was for users to eventually be able to specify their own
such associations, in addition to those (e.g. Unicode) that would be
predefined.

And it would be good to be able to use these not only for search but
also for easy replacement (in either direction of such an equivalence),
etc.  E.g., have easy access to such pairs via `M-%' - be able to
input one of such a class (char or char sequence) and then pick from
its defined equivalences for the replacement.