[I18n-sig] Re: [Python-Dev] Unicode debate

M.-A. Lemburg mal@lemburg.com
Tue, 02 May 2000 11:56:21 +0200


Fredrik Lundh wrote:
> 
> M.-A. Lemburg <mal@lemburg.com> wrote:
> > Just a small note on the subject of a character being atomic
> > which seems to have been forgotten by the discussing parties:
> >
> > Unicode itself can be understood as multi-word character
> > encoding, just like UTF-8. The reason is that Unicode entities
> > can be combined to produce single display characters (e.g.
> > u"e"+u"\u0301" will print "" in a Unicode aware renderer).
> > Slicing such a combined Unicode string will have the same
> > effect as slicing UTF-8 data.
> 
> really?  does it result in a decoder error?  or does it just result
> in a rendering error, just as if you slice off any trailing character
> without looking...

In the example, if you cut off the u"\u0301", the "e" would
appear without the acute accent, cutting off the u"e" would
probably result in a rendering error or worse put the accent
over the next character to the left.

UTF-8 is better in this respect: it warns you about
the error by raising an exception when being converted to
Unicode.
 
> > It seems that most Latin-1 proponents seem to have single
> > display characters in mind. While the same is true for
> > many Unicode entities, there are quite a few cases of
> > combining characters in Unicode 3.0 and the Unicode
> > normalization algorithm uses these as basis for its
> > work.
> 
> do we supported automatic normalization in 1.6?

No, but it is likely to appear in 1.7... not sure about
the "automatic" though.

FYI: Normalization is needed to make comparing Unicode
strings robust, e.g. u"" should compare equal to u"e\u0301".

-- 
Marc-Andre Lemburg
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