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Re: [ddlm-group] Wrapping up the elide discussion

If the choice is only between F and F', I vote for F.

To clarify:

James' F' proposal was:

"The datavalue is obtained from the triple-quoted string in two steps:
(1) All instances of <backslash><eol> are removed from the string
where the <backslash> is not preceded by another <backslash>
(2) All other instances of <backslash><eol> are replaced with <eol>

"This means that a sequence of n backslashes followed by newline is
replaced by a sequence of n-1 backslashes followed by newline, except
if there is one backslash before the newline, in which case both
newline and backslash are removed.  Triple quote sequences are elided
by inserting a <backslash><eol> sequence between <delimiter>
characters to break up the triple delimiter sequence.  Note also that
backslash has no special meaning if not in a sequence finishing with
<eol>."

Simon's F proposal was

"If you're looking to base CIF extensions on established mechanisms, 
why not adopt
the minimal \(newline) and \\ escape sequences, which in essence are 
the same as
the established CIF line-folding protocol (just dropping the initial 
\ following the opening
delimiter and formalising the protocol as an inherent part of the 
spec). Afterall, I beleive you
have already been using it, or at least interpreted it, as a means to 
escape 'semicolon delimiters' within
semicolon-delimited values (I seem to recall discussions that 
identified an issue with the published 'trip tests'
relating to line folding)."

Under Simon's F proposal

"""\\\
"""

would mean one backslash (no trailing new line)

and

"""\\
"""

would mean one backslash followed by a newline

and

"""\\

"""

would mean one backslash followed by two newlines

while under James' F'

"""\\\
"""

would mean two backslashes (no trailing newline)

and

"""\\
"""

would mean one backslash (no trailing newline)

and

"""\\

"""

would mean one backslash followed by a newline


While either proposal could, of course, be implemented, to me,
Simon's proposal is seems complete and more consistent with
common programming practice in handling backslash elides

I agree with James that it is time to make a choice and move
on.  I just hope, if we cannot follow complete Python
practice, we at least take F, the proposal that is more
consistent with Python practice.



At 7:57 AM -0500 1/30/11, Frances C. Bernstein wrote:
>Date: Sun, 30 Jan 2011 23:40:58 +1100
>From: James Hester <jamesrhester@gmail.com>
>Reply-To: Group finalising DDLm and associated dictionaries
>     <ddlm-group@iucr.org>
>To: ddlm-group <ddlm-group@iucr.org>
>Subject: [ddlm-group] Wrapping up the elide discussion
>
>Dear DDLm-ers,
>
>This latest round of discussion started as an attempt to find
>consensus on an elide system for CIF2 triple-quoted strings.  I have
>asked everybody to contribute their preferences, and now that John W
>and Ralf have replied to me off-list regarding their preferences for
>elides, we are in a position to read the tea-leaves and determine a
>consensus solution.  I can report that Ralf, while preferring the full
>Python approach (proposal P) will accept a solution that allows
>arbitrary strings to be included in a CIF file.  John W prefers a
>solution involving minimal changes to current syntax.
>
>So our top preferences are as follows:
>
>Herbert: P, otherwise F with conditions
>Brian: F' and E, P least preferable
>James: F' and F, P unacceptable
>Ralf: P best, A,B,E,F,F' OK
>John W: A, B or F' (my interpretation of minimal changes - John feel
>free to say otherwise)
>
>It appears that all but Herbert would be prepared to vote for F', and
>even Herbert is prepared to consider F.  No other proposal reaches a
>similar level of acceptance among voting members (and I note that
>non-voting members are also strongly in the F/F' camp).  I would
>therefore like to focus discussion on F' and F as the two choices most
>likely to succeed.
>
>The single point in favour of F' as opposed to F is that the sequence
><backslash><backslash> has no meaning, which makes it simpler to
>include backslash-rich text (eg LaTeX or RTF).  This continues to be
>of particular concern among our journal colleagues.
>
>The single point that some consider to be in favour of F relative to
>F' is that it is a proper subset of Python syntax.
>
>If no consensus can be achieved following a small period for comment
>within this group, I propose voting between F or F', followed by a
>formal vote at COMCIFS level to accept the resulting elide system as
>an amendment to the current CIF2 standard.
>
>James.
>
>--
>T +61 (02) 9717 9907
>F +61 (02) 9717 3145
>M +61 (04) 0249 4148
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-- 
=====================================================
  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@dowling.edu
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