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Re: [ddlm-group] Relationship of CIF2 to legacy platforms

Nick Spadaccini wrote:
> 
> 
> On 3/11/09 12:53 AM, "Joe Krahn" <krahn@niehs.nih.gov> wrote:
> 
>> Herbert,
>> I am only suggesting that maintained Fortran code ought to be able to
>> utilize F2003 STREAM I/O, supported by current versions of GFortran,
>> Intel Fortran and Sun Fortran.
>>
>> Of course, I probably am not considering all of the issues. STREAM I/O
>> avoids the need for a fixed maximum record length, but even the newest
>> Fortran compilers have very limited UTF-8 support. Even with STREAM I/O,
>> it is not trivial to count trailing blanks as significant.
>>
>> Maybe the biggest problem is UTF-8. IMHO, it makes sense for UTF-8 to be
>> an optional encoding, rather than just declaring CIF2 is all UTF-8. This
> 
> Not sure what you gain by doing this. If it is pure ASCII only then the
> declaration of UTF-8 inhibits nothing, since ASCII is a subset. If it is not
> pure ASCII, then it needs to be UTF-8. I can't see how knowing in advance
> that it is a subset of UTF-8 or possibly the full set of UTF-8 gives you
> anything.
> 
> cheers
> 
> Nick
A compiler/language not aware of UTF-8 could avoid errors by rejecting 
CIF files that contain UTF-8. However, I think the approach being taken 
is just to allow implementations to restrict usage, rather than put it 
in the specifications. For example, the plan seems to be that 
DDL/dictionary definitions will be used to avoid UTF-8 in data names, 
where it is most likely to be a problem. So, you are right: there is no 
reason for the CIF2 syntax to make UTF-8 optional when the dictionaries 
can restrict characters to the ASCII subset.

The other potential legacy issues I know of are fixed maximum line 
lengths, and significant trailing blanks. Dictionary definitions cannot 
avoid these. It might be possible to take a similar approach, by 
avoiding them by implementation conventions rather than making it part 
of the spec. If these are only going to be an issue for a few more 
years, it would avoid having to make another syntax change in the near 
future.

My main interest here is to avoid incompatible implementations. I also 
think that Fortran, and any other line-oriented I/O software, should be 
able to do stream-oriented I/O in the near future.

Joe

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