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Re: [ddlm-group] Technical issues with Proposal P

I'm sorry Herbert, I don't understand your answer.  Let me ask as
simply as possible.  Assume that a CIF application would like to pass
each of my example internal representations obtained from the parser
to a LaTeX processor for which <backslash><quote> means "place an
accent on the preceding character". Should that application remove the
<backslash> from the <backslash><quote> sequence on the grounds that
it was simply an elide?  Or should it keep the <backslash><quote> on
the grounds that the previous character should be accented?  How does
the application decide?

Note that IDLE is irrelevant as it is only giving you the
transformation from syntax to internal representation.  Discussion of
"cooked" versus "raw" is irrelevant as they relate only to the
transformation to internal representation.  I agree that the internal
representation is indeed *not* ambiguous. What I want to know is how a
downstream CIF program is supposed to interpret that internal
representation, given that the meaning of <backslash><delimiter> is
ambiguous.

I do not think appealing to other supposedly ambiguous aspects of the
CIF2 design helps Proposal P's case.  We would prefer no ambiguity
where we have a choice. We have a choice. We have proposal F on the
table which is unambiguous and a lot less work to implement.  I would
hope that the proponents of Proposal P are offering us something as
least as functional as F given the amount of extra work and complexity
involved to implement and maintain it.

On Tue, Feb 22, 2011 at 11:01 PM, Herbert J. Bernstein
<yaya@bernstein-plus-sons.com> wrote:
> Dear Colleagues,
>
>  Working under the assumption of Ralf's proposal, rather
> than Simon's, we have several very distinct string presentaions
> to consider:  a (non-raw) treble quoted string, a raw treble
> quoted string a unicode treble quoted string and a raw unicode
> treble quoted string.  As for Python 3, under CIF2, because
> the "native" character encoding is UTF-8, under reasonable coding
> constraints, this collapses to just two cases the application
> needs to deal with:  non-raw (i.e. cooked) versus raw.  The intent of
> the cooked is for the lexer to process the elides, so the response
> I gave is, I believe correct -- just push the string through IDLE.
> The intent of the raw is precisely to push through the string
> with the backslahes still in place, e.g. for TeX text in which
> you don't want to double-up your backslashes.  While I personally
> would recommend against such a use of raw, it is not ambiguous.
> It gives the application a very well-defined string of characters
> to deal with.  Yes, there are applications that are intended to
> deal with CIF with the encoding exposed (e.g. cif2cbf, cif2cif, etc.)
> bit, I agree that the cleanest design is for an application to
> only make use of the string content, not the representation.
>
>  Thus, for most applications, I would recommend that they treat
>
>  """\\\"""" and r"""\""""
>
> as equivalent, but for applications that are, for example,
> intended to do faithful copies of the representations that
> they treat them as different.
>
>  We have had, and will continue to have this subtle problem
> with all versions of CIF in the handling of things such as
> magic number, comments, white space, line folding, and choices
> of quoting characters.  I don't see how the introduction of
> the Python treble quote makes the situation any worse or
> any more or less ambiguous.
>
>  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@dowling.edu
> =====================================================
>
> On Tue, 22 Feb 2011, James Hester wrote:
>
>> I will focus this email on the technical issues and try to return to
>> the other issues at a later date (I've changed the subject
>> accordingly)
>>
>> [edit]
>>
>> My apologies for not being clear: my examples of embedded elides
>> already give the internal representation of the strings, deliberately
>> leaving out the particular delimiters that might have been used to
>> produce those strings.  Herbert mistakenly thought I was giving
>> triple-double-quote delimited strings and asking what the internal
>> representation was. So, unfortunately, IDLE cannot help here, as the
>> internal representation is not in question.
>>
>> My question therefore remains: how does the CIF application interpret
>> these strings? Is the <backslash><delimiter> in my examples simply an
>> elide that could not be removed from a raw string and therefore should
>> be ignored, or is it a character sequence intended for the application
>> (eg a LaTeX accent on the o or e)?
>>
>> In your answer you may assume that the CIF application knows that the
>> string was a raw string delimited by triple double quotes (even though
>> requiring communication of such information would be a very
>> unfortunate loss of clean design).
>>
>> Those strings again:
>>
>> <start> I have no idea what the last characters of this string
>> are\"<finish>
>> <start> Does this string have two\""" or three internal quotes?<finish>
>>
>>
>> Herbert writes:
>>>
>>>   Now for your two examples of embedded elides of quotes:
>>>
>>> <start> I have no idea what the last characters of this string
>>> are\"<finish>
>>>
>>> is, internally, as a C-string
>>>
>>> I have no idea what the last characters of this string are"\0
>>>
>>> <start> Does this string have two\""" or three internal quotes?<finish>
>>>
>>> is, internally as a C-string
>>>
>>> Does this string have two""" or three internal quotes?\0
>>>
>>> I settled that by simply cranking up IDLE and doing:
>>>
>>>>>>  print """I have no idea what the last characters of this string
>>>>>> are\"""" I have no idea what the last characters of this string
>>>>>> are" >>> print """Does this string have two\""" or three internal
>>>>>> quotes?""" Does this string have two""" or three internal quotes?
>>>
>>> As you well know, having IDLE around is a big help.
>>>
>>>   Thank you again for taking the time to clarify your position
>>> on Ralf's proposal.  I think I now understand why you prefer Simon's
>>> proposal.
>>>
>>>   Regards,
>>>     Herbert
>>>
>>>
>>>
>>>
>>>
>>
>>>> One technical issue with Proposal P that has not been resolved is how
>>>> a CIF application is supposed to interpret the sequence
>>>> <backslash><double quote> when encountered in a string returned from
>>>> the parser.  Is this sequence:
>>>> (a) a terminator elide sequence that was left in a raw string, so
>>>> corresponds to <double quote>?
>>>> (b) something with meaning for the application so should be
>>>> <backslash><double quote>?
>>>>
>>>> Please therefore advise how a CIF application will disambiguate the
>>>> following string content from a Proposal P parser:
>>>>
>>>> <start> I have no idea what the last characters of this string
>>>> are\"<finish>
>>>> <start> Does this string have two\""" or three internal quotes?<finish>
>>>>
>>>> James
>>>>
>>
>>
>>
>> --
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