[Python-Dev] should we keep the \xnnnn escape in unicode strings?

Greg Stein gstein@lyra.org
Sun, 16 Jul 2000 14:19:22 -0700

To me, this says punt the \x construct from Unicode objects altogether. If
it is broken, then why try to retain it?

I *do* find it useful in the regular string objects. For Unicode, I would
totally understand needing to use \u instead.


On Sun, Jul 16, 2000 at 02:14:02PM -0400, Tim Peters wrote:
> [/F]
> >     for maximum compatibility with 8-bit strings and SRE,
> >     let's change "\x" to mean "binary byte" in unicode string
> >     literals too.
> [MAL]
> > Hmm, this is probably not in sync with C9X (see section,
> The behavior of \x in C9X is nearly incomprehensible -- screw it.
> > but then perhaps we should depreciate usage of \xXX in the context
> > of Unicode objects altogether. Our \uXXXX notation is far
> > superior to what C9X tries to squeeze into \x (IMHO at least).
> \x is a hack inherited from the last version of C, put in back when they
> knew they had to do *something* to support "big characters" but had no real
> idea what.  C9X was not allowed to break anything in the std it built on, so
> they kept all the old implementation-defined \x behavior, and made it even
> more complicated so it would make some kind sense with the new C9X character
> gimmicks.
> Python is stuck trying to make sense out of its ill-considered adoption of
> old-C's \x notation too.  Letting it mean "a byte" regardless of context
> should make it useless enough that people will eventually learn to avoid it
> <wink>.
> Note that C9X also has \u and \U notations, and \u in C9X means what it does
> in Python, except that C9X explicitly punts on what happens for \u values in
> these (inclusive) ranges:
>     \u0000 - \u0020
>     \u007f - \u009f
>     \ud800 - \udfff
> \U is used in C9X for 8-digit (hex) characters, deferring to ISO 10646.
> If C9X didn't *have* to keep \x around, I'm sure they would have tossed it.
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Greg Stein, http://www.lyra.org/