On Thu, 3 Dec 2009, Eric Blake wrote:
Thomas Dickey <dickey <at> his.com> writes:
This means that characters 0..127 have to be treated as ASCII, but
No, it means that portable characters and control characters must be < 128.
ASCII meets this characteristic, but so does EBCDIC, as well as UTF-8. The C
locale also implies that you can manipulate bytes >= 128 in the naive manner,
so long as you don't care about characters embedded in those bytes. And what
do you know - ASCII, EBCDIC, and UTF-8 all meet this property, too.
beyond that an implementation can do what it wants. And on Cygwin 1.7,
plain "C" actually does imply UTF-8, which happily is
backward-compatible with ASCII.
That's an interpretation that so far hasn't been blessed by the standards
people. Any discussion of this topic should mention that, as a caveat.
Actually, the standards people HAVE spoken - and they agreed with our
interpretation. POSIX was INTENTIONALLY written with the intent that a UTF-8
encoding is valid for the C locale, for the same reason that it was written
that an EBCDIC encoding is valid for the C locale. These emails from the
Austin Group (the folks that write POSIX) are telling:
https://www.opengroup.org/sophocles/show_mail.tpl?
CALLER=show_archive.tpl&source=L&listname=austin-group-l&id=12982
This is basically your email on the matter.
https://www.opengroup.org/sophocles/show_mail.tpl?
CALLER=show_archive.tpl&source=L&listname=austin-group-l&id=13012
But they also admitted that there is still more work needed in POSIX to make
this intent clearly codified (for example, that control characters must be
single bytes < 128).
But they have not actually agreed with you yet.
--
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net
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