break unichr instead of fix ord?

Mark Tolonen metolone+gmane at gmail.com
Wed Aug 26 05:53:52 CEST 2009


<rurpy at yahoo.com> wrote in message 
news:2ad21a79-4a6c-42a7-8923-beb304bb5e99 at v20g2000yqm.googlegroups.com...
> In Python 2.5 on Windows I could do [*1]:
>
>  # Create a unicode character outside of the BMP.
>  >>> a = u'\U00010040'
>
>  # On Windows it is represented as a surogate pair.
>  >>> len(a)
>  2
>  >>> a[0],a[1]
>  (u'\ud800', u'\udc40')
>
>  # Create the same character with the unichr() function.
>  >>> a = unichr (65600)
>  >>> a[0],a[1]
>  (u'\ud800', u'\udc40')
>
>  # Although the unichr() function works fine, its
>  # inverse, ord(), doesn't.
>  >>> ord (a)
>  TypeError: ord() expected a character, but string of length 2 found
>
> On Python 2.6, unichr() was "fixed" (using the word
> loosely) so that it too now fails with characters outside
> the BMP.
>
>  >>> a = unichr (65600)
>  ValueError: unichr() arg not in range(0x10000) (narrow Python build)
>
> Why was this done rather than changing ord() to accept a
> surrogate pair?
>
> Does not this effectively make unichr() and ord() useless
> on Windows for all but a subset of unicode characters?

Switch to Python 3?

>>> x='\U00010040'
>>> import unicodedata
>>> unicodedata.name(x)
'LINEAR B SYLLABLE B025 A2'
>>> ord(x)
65600
>>> hex(ord(x))
'0x10040'
>>> unicodedata.name(chr(0x10040))
'LINEAR B SYLLABLE B025 A2'
>>> ord(chr(0x10040))
65600
>>> print(ascii(chr(0x10040)))
'\ud800\udc40'

-Mark





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