CIF2 syntax document for COMCIFS approval
Herbert J. Bernstein
yaya at bernstein-plus-sons.com
Mon Dec 27 23:21:55 GMT 2010
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."
Regards,
Herbert
=====================================================
Herbert J. Bernstein, Professor of Computer Science
Dowling College, Kramer Science Center, KSC 121
Idle Hour Blvd, Oakdale, NY, 11769
+1-631-244-3035
yaya at dowling.edu
=====================================================
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 at gmail.com>
>> To: Discussion list of the IUCr Committee for the Maintenance of the CIF
>> Standard (COMCIFS) <comcifs at 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
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