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


On Tuesday, February 22, 2011 4:55 PM, James Hester wrote:

>I am trying to focus relentlessly on a particular and very real
>technical issue.  I repeat that I am not concerned about the
>transformation from surface syntax to a sequence of characters.  I
>accept that that is well-defined and unambiguous for all proposals on
>the table.  If you think that IDLE can resolve this problem, you
>haven't understood my question.
>
>My question relates to the next step: how does the CIF application
>downstream from the parser interpret this sequence of characters?
>Under all previous incarnations of CIF, it was safe to assume that no
>artefacts of syntactical representation were left in the string, so
>the string had purely domain-specific meaning.  However, with the
>introduction of raw strings, <backslash><delimiter> will escape the
>delimiter, but the <backslash> is required to remain in the string.

I'm good this far.

>So the downstream application must decide between artefacts of the
>syntactical representation (<backslash><delimiter>) that have remained
>in raw strings, and domain-specific character sequences
>(<backslash><delimiter>).

And this is where the disconnect occurs.  I hold, and I interpret Herbert and Simon also to hold, that it is incorrect to characterize the backslash in the parsed data value as an artifact: it is rather an intended member of the string's character data.  Backslashes in Python raw strings serve simultaneously as elides and character data.  If an lexical-level eliding backslash is not intended to be part of an application-level data value, then raw string syntax is not suitable for expressing that value.

This is an odd and I think confusing feature that I am not eager to add to CIF, but I don't think it creates any technical ambiguity.

>  Here those examples are again (remember
>this is the character sequence after syntactic processing):
>
> <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>
>
>Assume the domain-specific meaning of <backslash><quote> when found in
>a datavalue is to accent the letter preceding the <backslash>.
>
>Does the first string finish with a double quote, or with an accented e?

The domain-specific meaning is that it ends with an accented e.

>Does the second string contain an accented o, followed by two double
>quotes, or a letter o followed by three quotes?

The domain-specific meaning is that it contains an accented o, followed by two quotes.


John

--
John C. Bollinger, Ph.D.
Department of Structural Biology
St. Jude Children's Research Hospital


Email Disclaimer:  www.stjude.org/emaildisclaimer

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