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Re: CIF2 syntax document for COMCIFS approval

Dear Ralf,

   Without the treble quotes, the new quoting syntax leaves such
large gaps in the handling of existing data sets, I would then
have to change my vote to "no".   Personally, I would prefer
to simply adopt the python quoting syntax in its entirety including
both unicode and raw string support, but I cannot see that
happening until and unless we have a meeting to thrash out
everybody's concerns.

   I agree that the lack of backslash handling in the syntax as
an escape at the lexical level is a mistake, but after more than 4 years 
of trying to get one adopted, I don't think it is realistic to hold up 
everything else in CIF2 and DDLm in order to try to force through a 
settlement of that issue.  I think that will just delay CIF2 for another 
several years.

   Therefore I suggest that we adopt CIF2 as it now stands, without the use 
of the backslash as an escape at the lexical level, but add the 
following caution to users and developers:

    "CIF2 as it now stands does not provide a common, agreed
syntax for the handling of reverse solidus (aka backslash)
escape syntax at the lexical level.  There is a significant
possibility that an approach to the handling of the reverse
solidus may be adopted in a future version of CIF that will
require some changes in the syntax of delimited strings.  Users and
developers are cautioned that such a future version of CIF
may require the "doubling" of each reverse solidus in
a delimited string to retain the current meaning.  If
such a change is made, a utility to make the necessary
conversions will be provided."


  Herbert J. Bernstein, Professor of Computer Science
    Dowling College, Kramer Science Center, KSC 121
         Idle Hour Blvd, Oakdale, NY, 11769


On Mon, 27 Dec 2010, Ralf W. Grosse-Kunstleve wrote:

> After careful consideration I vote "no" on the proposed new CIF syntax,
> although I agree with the general direction. I'm deeply concerned about
> introducing new syntax for delimiting strings without solving a
> long-standing problem. James explained to me that the "extra
> multi-line text delimiters are provided to further reduce the likelihood of
> running into text that is impossible to delimit." I strongly believe that
> the problem needs to be solved completely, for example by adopting the
> widely used backslash escape semantics.
> I would agree to the proposal after either
>  - an escape mechanism for the new triple-quoted strings is added or
>    alternatively
>  - the new triple-quote syntax is removed, so that it can be introduced
>    later with an associated escape mechanism.
> Ralf
> ----- Original Message ----
>> From: James Hester <jamesrhester@gmail.com>
>> To: Discussion list of the IUCr Committee for the Maintenance of the CIF
>> Standard (COMCIFS) <comcifs@iucr.org>
>> Sent: Tue, November 16, 2010 3:28:32 PM
>> Subject: CIF2 syntax document for COMCIFS approval
>> Dear COMCIFS,
>> After more than a year of discussion, the DDLm working  group has
>> converged on a specification for a new CIF syntax, dubbed  "CIF2".  The
>> one-page document describing the changes relative to CIF1  is available
>> on the IUCr website  at
>> http://www.iucr.org/__data/assets/pdf_file/0004/47434/cif2_syntax_changes_jrh20101115.pdf.
>> .
>> A  record of the extensive discussions of the DDLm working group is
>> available  at http://www.iucr.org/resources/lists/ddlm-group, with
>> encoding-specific  discussions taking place  at
>> http://www.iucr.org/resources/lists/cif2-encoding
>> This CIF2  specification is now presented to COMCIFS for approval. I
>> urge all COMCIFS  voting members to register their vote in a timely
>> fashion.
>> James  Hester
>> COMCIFS Chair
>> --
>> T +61 (02) 9717 9907
>> F +61 (02) 9717  3145
>> M +61 (04) 0249  4148
>> _______________________________________________
>> comcifs mailing  list
>> comcifs@iucr.org
>> http://scripts.iucr.org/mailman/listinfo/comcifs
> _______________________________________________
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> comcifs@iucr.org
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