[Python-Dev] unicode alphanumerics

M.-A. Lemburg mal@lemburg.com
Mon, 03 Jul 2000 12:38:04 +0200

"M.-A. Lemburg" wrote:
> Fredrik Lundh wrote:
> > how about this plan:
> >
> > -- you add a Py_UNICODE_ALPHA to unicodeobject.h asap,
> >    which does exactly that (or I can do that, if you prefer).
> >    (and maybe even a Py_UNICODE_ALNUM)
> (first with approximations of the sort you give above and
> later with true implementations using tables in unicodectype.c)
> on Monday... gotta run now.
> > -- I change SRE to use that asap.
> >
> > -- you, I, or someone else add a better implementation,
> >    some other day.

I've just looked into this... the problem here is what to
consider as being "alpha" and what "numeric". 

I could add two new tables for the characters with category 'Lo'
(other letters, not cased) and 'Lm' (letter modifiers)
to match all letters in the Unicode database, but those
tables have some 5200 entries (note that there are only 804 lower
case letters and 686 upper case ones).

Note that there seems to be no definition of what is to be
considered alphanumeric in Unicode. The only quote I found was
in http://www.w3.org/TR/xslt#convert which says:

Alphanumeric means any character that has a Unicode
category of Nd, Nl, No, Lu, Ll, Lt, Lm or Lo.

Here's what the glibc has to say about these chars:

/* Test for any wide character for which `iswupper' or 'iswlower' is
   true, or any wide character that is one of a locale-specific set of
   wide-characters for which none of `iswcntrl', `iswdigit',
   `iswpunct', or `iswspace' is true.  */
extern int iswalpha __P ((wint_t __wc));

Should I go ahead and add the Lo and Lm tables to unicodectype.c ?

Pros: standards confrom
Cons: huge in size

Marc-Andre Lemburg
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