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Re: Universal Character Names, v2


"Martin v. =?iso-8859-15?q?L=F6wis?=" <martin@v.loewis.de> writes:

> - Support UCNs in numbers. In the internal represantation, such
>   a number still has the UCN in it, i.e. no conversion to UTF-8
>   takes place. Such numbers will only be valid if they are pasted
>   with an identifier.

Is this intended to be an extension to C99?  I think it is; C99
doesn't support things that start with digits and then contain
non-digits (as specified by C99) in them.  I believe that support for
more kinds of digit was explicitly considered and rejected by the C
standards committee, on the grounds that (a) it provides no useful
functionality, and (b) it makes it harder to process C source files
without having a full C tokenizer, because now even recognizing the
start of a number requires full UCN processing.

> - I have not decided to deviate from the C and C++ standards for
>   character tests. Reviewers commented that they dislike the approach
>   taken by the standards committees, and that the relevant Unicode
>   specification should be taken into account instead. I disagree, as I
>   consider the approach of giving explicit lists quite reasonable.
>   More importantly, I think that standards conformance should be
>   valued quite highly unless specific user demands require to
>   ignore or extend the standards; this is not the case in the
>   specific issue.

I support this approach.  The C standards committee considered the
matter, and decided that it was better to have a fixed, limited, set
of characters that could be allowed in identifiers, rather than a
language definition that varies as ISO10646 is updated, causing some
implementations to be incorrect simply because they didn't have the
latest ISO10646 code tables.

-- 
- Geoffrey Keating <geoffk@geoffk.org>


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