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Re: CIF line limits



The use of Fortran on platforms that support C-iterfaces with differing
approaches is a reality, especially in the physical sciences.  I would
suggest that those who propose very large, or unlimited line lengths, and
other new features release or point us to appropriate open-source APIs for
Fortran (and, of course C) applications, and explain how files written to
the specifications they propose will be handled by the various popular text
editors, such as notepad, pico, BBEdit, emacs and vi.

With some precision in specification, I believe that Brian's line
continuation by use of a backslash would be a very good step towards
resolving these differing views.

As to unlimited tag lengths, I believe we may need to adopt the compromise
used in many existing languages, of relaxing the lengths of tags as
presented in files, but of considering only some fixed initial portion of
each tag as being significant to parsers.

Regards,
    Herbert

At 17:00 +0000 11/16/00, Nick Spadaccini wrote:
>On Thu, 16 Nov 2000, I. David Brown wrote:
>
>> 	However, life is never simple.  Bernstein pointed out that some
>> platforms cannot handle unlimited lines and that some large formal limit
>> was still needed (he proposed 200 characters).  McMahon was concerned to
>
>Actually David, this discussion dates back to 1992, and the members of
>discussion list need to be reminded that STAR (upon which CIF is
>based) has never had any line length restriction nor any dataname length
>restriction. The software built for STAR has always fulfilled the
>requirements of this specification and it is hard to see why in Y2000
>CIF *needs* any restrictions. So my vote (and since I am not a
>voting member that doesn't say much) is that any restrictions be removed.
>
>Herb's concerns are directed purely at Fortran programmers, and in
>particular those that do not use the C library extensions. Fortran's IO
>has always been arcane since it needs to think in terms of records rather
>than a stream of bytes. However to restrict a universal file specification
>because of the limitations of one programming language seems rather short
>sighted. Quite frankly in terms of sound practice, extending the limit
>from 80 to 200 is no different to extending it from 80 to 81! Eventually
>someone's going to want a record that is 201 bytes. As a matter of
>interest how many other file formats that people in this discussion list
>deal with have line length restrictions?
>
>> introduce a formal way in which the longer lines could be broken down into
>> shorter lines to allow existing software to handle the new types of file.
>
>The reasoning is a little fuzzy. There exists software which will not be
>changed to meet the new specification. There exists files with greater
>than 80 byte lines. So how is that software going to read this file? Since
>the file isn't going to miraculously break itself down to shorter lines,
>someone else will have to write a program that is able to read the file
>properly, and hack it into a form so that existing software doesn't have
>to updated. And the sum total of this is .....
>
>>                                          Datanames are still effectively
>> limited to 80 characters since there is no mechanism for them to be split
>> between lines.
>
>You guessed it, another artificial limit needs to be introduced (or
>extended)! Rather than write software that does the job properly, just so
>it can write files for software that doesn't do its job properly let the
>IUCr actively insist all software that claims to be CIF compatible adopt
>the new specification. That way datanames need NOT be restricted to any
>length.
>
>>            All agreed also that there were good stylistic reasons for
>> CIFs to observe the 80 character limit where possible, even if longer
>> lines were approved, since wrap-around can be a problem for printers and
>> screens.
>
>But Brian's suggestion of "eliding" line terminations does have stylistic
>merits. However its purpose is purely stylistic and should not be an
>encouragement for people to continue to write or support software that
>does not meet the new CIF specification. Moreover the semantics of the
>elided line terminations needs to be pinned down. For instance Unix shells
>like csh, tcsh and tcl replace the elide digraph with a space, whereas zsh
>and bash replace it with a null (which is Herb's favoured option if I
>recall).
>
>> 	I am therefore bringing forward two proposals for discussion:
>>
>> 1. That the different CIF versions be numbered with 1.0 being the original
>> CIF definition, and 1.1 the version that extends dataname lengths from 32
>> to 80 characters.  These two versions currently exist but do not have
>> version numbers.
>>
>> 2. That version 2.0 increase the line limit from 80 characters to 200
>> characters.
>
>I can see no strong reason why there should be any limit imposed on line
>lengths or dataname lengths. There isn't in STAR, and there isn't in many
>other *modern* file standards I deal with.
>
>cheers
>
>Nick
>
>--------------------------------
>Dr Nick Spadaccini
>Department of Computer Science              voice: +(61 8) 9380 3452
>University of Western Australia               fax: +(61 8) 9380 1089
>Nedlands, Perth,  WA  6907                 email: nick@cs.uwa.edu.au
>AUSTRALIA                        web: http://www.cs.uwa.edu.au/~nick


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