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Re: [ddlm-group] Focusing the elide discussion

Thanks Brian for this thorough reply.  How fortunate for us that
England do not have high-speed trains.  Now I'm just waiting for John
W to give his thoughts.

On Tue, Jan 18, 2011 at 11:05 PM, Brian McMahon <bm@iucr.org> wrote:
> Dear James
>
> Sorry for the delay in replying to this request. A long train
> journey yesterday gave me the opportunity to review the
> discussions on this point. In order of preference I would
> rank the proposals as roughly:
>
> F'    - requires least handling of special escapes
> E     - allows the generic handling of Unicode character set and
>        long lines as native CIF2 features (but only within "special"
>        i.e. triple-quote delimited strings)
>
> I think these allow embedding of any string in a reasonably clean way.
>
> C     - I quite like, provided the post-elide escape could be a sequence
>        (e.g. borrowing from TeX, the trigraph "{} is read as a
>         double-quote; the literal sequence
>        <doublequote><open brace><close brace> would be represented by "{}{}
>        and any other sequence would have no special meaning). If those with
>        greater experience argue that this imposes too great a load on the
>        initial lexical scan, or can demonstrate that this leads too
>        quickly to a proliferation of unreadable punctuation marks,
>        this would drop quickly down the lilst of preferred approaches).
> F     - because I'm not sure what is gained just by protecting the
>        escape character everywhere; but on the other hand it may seem
>        an easy procedure to describe to potential implementors
> A
> B     - carries an unwelcome overhead in requiring the escape character
>        (here, backslash) to be encoded everywhere
>
> D
>
> P     - brings in unnecessary syntactiv overhead when we can achieve a
>        closed system by simpler means.
>
> Best wishes
> Brian
>
>
>
> On Thu, Jan 13, 2011 at 12:20:09AM +1100, James Hester wrote:
>> By my count there are 6 distinct proposals for eliding triple-quoted
>> strings on the table, which I have listed below.  In order to get an
>> idea of where we all stand and which proposals are most likely to
>> succeed, I'd like to invite you all to reply to this email with a list
>> of proposals which you would find acceptable.  If you like, you can
>> rank them in order of preference.  In the list below I've given short
>> descriptions, but you should refer to the original emails for the full
>> details.  The opinions of COMCIFS voting members are of course most
>> significant at this juncture, but I for one am interested in the
>> thoughts of the other members as well.
>>
>> Proposal P (for Python): Ralf's original proposal to do everything as in Python
>> Proposal A: <backslash><delimiter> elides the delimiter, no other
>> sequences are significant
>> Proposal B: \uxxxx to represent Unicode characters, no other sequences
>> are significant
>> Proposal C: as yet unspecified character post-elides the delimiter
>> where necessary
>> Proposal D: as for C, except post-elide character is given immediately
>> before opening triple delimiter
>> Proposal E: (John B's suggestion) \uxxxx for Unicode character
>> together with \<newline> and \\
>> Proposal F: (Simon's proposal) \<newline> and \\ only
>> Proposal F': (My slight tweak of Simon's proposal) \<newline> only
>> when not preceded by \
>>
>> I find proposal P unacceptable, and would rank the others in order of
>> preference roughly as follows:
>>
>> Best: F', F, C
>> Bearable: A, B, E
>> In a pinch: D
>>
>> --
>> T +61 (02) 9717 9907
>> F +61 (02) 9717 3145
>> M +61 (04) 0249 4148
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M +61 (04) 0249 4148
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