Re: Display-based word wrapping

[Chong Yidong <cyd@stupidchicken.com>]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>>> I don't see much of a problem with it.  That's what
>>> define-obsolete-variable-alias is for, isn't it?
>
>> Leaving these calls in place would generate plenty of byte-compiler
>> warnings, unless we do defvaralias instead of
>> define-obsolete-variable-alias.  Anyway, isn't it a general policy to
>> change the code in Emacs to use non-obsolete names?
>
> Of course, but luckily we have a tool (Emacs) that can help us do the
> search&replace for those cases that occur within Emacs's own files.
> Still doesn't seem like a major problem.
>
> Of course, we could also decide not to rename the variable.  All I'm
> after is to keep a single (3-state) variable rather than a pair of
> boolean vars to choose between the 3 alternative ways to deal with long
> lines.

What I'm questioning is whether it's truly a 3-state situation.  From
the point of view of the redisplay engine, yes, it's just three
different ways of wrapping.  But from the point of view of the Lisp
interface, it may be more convenient to regard word-wrap and char-wrap
are two different styles of line continuation, and to draw an additional
distinction between line continuation and line truncation.  Because then
the semantic role of truncate-partial-width-windows and
toggle-truncate-lines would be unchanged: if lines are not truncated,
they are continued, and the word-wrap variable determines how that
continuation occurs.