bug#1727: 23.0.60; end-of-sentence and non-breaking space

bug#1727: 23.0.60; end-of-sentence and non-breaking space

[Chong Yidong]

From bug#1726 and bug#1727:

> forward-sentence does not treat non-breaking space as a space for
> purposes of sentence ends.
...
> When I type C-x = at a non-breaking space, it tells me that it
> has code 160, hex a0.  But when I execute (insert "\xa0"),
> it inserts something that displays as `\240' and for which C-x =
> displays this:
>
>    Char:   (4194208, #o17777640, #x3fffa0, raw-byte) point=198 of 211
>    (93%) column=5
>
> Is that a bug?  It seems quite confusing to me.

ISTR that there was an extended discussion about classifying
non-breaking spaces on this list a while back.  But I can't find it now.
Does anyone remember the details?

bug#1727: 23.0.60; end-of-sentence and non-breaking space

[Richard M Stallman]

    > When I type C-x = at a non-breaking space, it tells me that it
    > has code 160, hex a0.  But when I execute (insert "\xa0"),
    > it inserts something that displays as `\240' and for which C-x =
    > displays this:

    >    Char:   (4194208, #o17777640, #x3fffa0, raw-byte) point=198 of 211
    >    (93%) column=5
    >
    > Is that a bug?  It seems quite confusing to me.

    ISTR that there was an extended discussion about classifying
    non-breaking spaces on this list a while back.  But I can't find it now.
    Does anyone remember the details?

I am not sure we are talking about the same question.
The issue I am raising is not one of classifying it,
it is that these two different character codes get used
and I don't see an explanation of what's going on.

bug#1727: 23.0.60; end-of-sentence and non-breaking space

[Drew Adams]

> ISTR that there was an extended discussion about classifying
> non-breaking spaces on this list a while back.  But I can't 
> find it now. Does anyone remember the details?

Dunno if this is what you were thinking of, but there was this discussion about
treating (classifying) nonbreaking space as whitespace:

http://lists.gnu.org/archive/html/emacs-devel/2007-06/msg01089.html

bug#1727: 23.0.60; end-of-sentence and non-breaking space

[Stefan Monnier]

>> has code 160, hex a0.  But when I execute (insert "\xa0"),
>> it inserts something that displays as `\240' and for which C-x =
>> displays this:
>> 
>> Char:   (4194208, #o17777640, #x3fffa0, raw-byte) point=198 of 211
>> (93%) column=5
>> 
>> Is that a bug?  It seems quite confusing to me.

This raw-byte char is what used to be called an eight-bit-control (or
eight-bit-graphic depending on the actual value) char.

I.e. "\xa0" is treated as a string that contains the \xa0 byte (i.e. an
eight-bit-* (aka raw-byte) char) rather than the \xa0 char (a latin-1
non-breaking space).


        Stefan