NEWBIE: ishexdigit revisited

[Jeff Epler]

The only suggestion I would make is to skip calculating ix and instead
just use len(sx).  The length of a string is already stored, so it
doesn't require Python to count the number of chars again (unlike C's
strlen()).

Well, actually, I'll make two suggestions:  If it's an error in some
cases to have an extra nibble, I'd use a 'raise' statement instead of a
different return value, something like:

    def ishexdigit(sx, silent=True):
        for cx in sx:
            if not cx in '0123456789abcdefABCDEF': return False
        if silent or len(sx) % 2 == 0: return True
        raise ValueError, "Extra nibble in '%s'" % sx

Now, ishexdigit('0') or ishexdigit('0', True) will return 1,
and ishexdigit('0', False) will cause an exception.

Jeff