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Re: [ddlm-group] Space as a list item separator

Dear Colleagues,

   I am also more comfortable with an "minimally disruptive" or 
"incremental" approach, so the only shouting I will do is to shout with 
joy if this group should choose to follow a such an approach.

   I am willing to abide by the decisions already made, but, if this group 
chooses to reopen the decisions that were made over the past several 
weeks, I believe we can work out an approach to DDLm and CIF2 that has the 
following useful combination of charateristics:

   1.  All existing CIF 1, CIF 1.1, imgCIF and CBF files can either be 
processed directly without change, or in a small number of easily 
identified cases will need some very minor changes on the level of, say, 
having to quote data values that begin with '(' or '{'

   2.  Within bracketed constructs, the rules for both quoted and 
non-quoted strings are similar to the rules at the top level, but a 
non-quoted string will be stopped by any of

    blank, tab, end of line, comma, colon, ], }, {, [

and a quoted string will be stopped by the terminal quoting symbol 
followed by any of the same list of characters.

Perhaps, one way to do this to satisfy all concerned, would be to
call what I just described, CIF 1.5 and to float the maximally
disruptive version we have been working on as CIF 2.

The open question would be how best to integrate dREL with CIF 1.5
and CIF 2 -- one simple compromise would be to say that dREL only
applies to tags and values conforming entirely to CIF 2 rules
in both cases, so that dREL methods could be used freely in a
CIF 2, but might not be applicable to all tags in a CIF 1.5, and
that some values would have to be manually or automatically quoted
before being processed by dREL methods working on a CIF 1.5 data
file.

It would be very reasonable to require the new dictionaries to
conform to CIF 2 rules.

   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 Sat, 28 Nov 2009, SIMON WESTRIP wrote:

> Dear all
> 
> I was chatting with the man who 'writes the cheques' yesterday about 
> some of the changes he might expect with CIF2, and based on this I feel 
> I ought to at least have a go at exploring a 'minimally disruptive' 
> approach, so at the risk of being shouted at, here goes at a slightly 
> different way of looking at CIF:
> 
> CIF contains a list of strings separated by whitespace.
> 
> A string can be nondelimited or delimited.
> 
> Nondelimited strings have a restricted character set (minimally whitespace
> is excluded)
> 
> A nondelimited string cannot start with any of the delimiters (obviously)
> 
> Nondelimited strings can have special meaning governing what follows them:
> 
>     reserved words, e.g. loop_
> 
>     tags, e.g. data_ , _foo
> 
>     single-byte nondelimited strings, e.g. [ ] { } :
> 
> All other strings are treated as raw data values
> 
> 
> There, least I can say I tried :-)
> 
> Cheers
> 
> Simon
> 
> ____________________________________________________________________________
> From: SIMON WESTRIP <simonwestrip@btinternet.com>
> To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
> Sent: Saturday, 28 November, 2009 10:01:38
> Subject: Re: [ddlm-group] Space as a list item separator
> 
> I had been under the assumption that the separation of list items by a comma
> was 'set in stone'
> (and was one reason for dropping the CIF1 syntax of requiring space after
> data values),
> but if its up for negotiation I would opt for using the space as a separator
> as elsewhere in the CIF,
> partly because then a list can essentially be treated much like a
> single-item loop - i.e. same basic parsing
> of <value><space><value><space>...
> 
> Cheers
> 
> Simon
> 
> ____________________________________________________________________________
> From: Herbert J. Bernstein <yaya@bernstein-plus-sons.com>
> To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
> Cc: Nick.Spadaccini@uwa.edu.au
> Sent: Friday, 27 November, 2009 11:43:10
> Subject: Re: [ddlm-group] Space as a list item separator
> 
> Dear Colleagues,
> 
>   I have no objection to accepting either comma or whitespace
> as a valid separator in a list.  I can't object -- I have been
> coding to that standard since 1997, and now would only have to
> remove the message generated for the case of the space.  We already
> accept multiple glyphs as valid separators at all levels:
> 
>   whitespace itself it one of several character sequences in rather
> complex combinations:  any number of blanks, tabs, newlines and comments.
> The comma itself is handled in a complex way.  We accept (or should accept)
> any whitespace before and after a comma as valid, as in
> {a,b} versus {a , b }.  Adding the option of leaving out the comma
> itself and just having the whitespace as the separator make just
> as much sense.
> 
>   I see nothing to be gained by now forbidding the comma.  The meaning of
> {a,,b,} is the same as {a,.,b,.} or {a,?,b,?} or, under this new (and I
> think more sensibsle and realistic approach) {a . b .} or {a ? b ?}.
> 
>   The blank reads particularly well in dealing with vectors and matrices.
> The comma reads well when dealing with strings.
> 
>   I think we would do best with both as valid alternatives (no error, no
> warning for either one).
> 
>   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 Fri, 27 Nov 2009, SIMON WESTRIP wrote:
> 
> > At first glance, you're considering using space instead of commas as list
> > separators?
> > which is not so far away from the CIF1 requirement of space following a
> > delimiter?
> >
> > But I'm only on my first cup of coffee this morning :-)
> >
> >___________________________________________________________________________
> _
> > From: Nick Spadaccini <nick@csse.uwa.edu.au>
> > To: Group finalising DDLm and associated dictionaries
> <ddlm-group@iucr.org>
> > Sent: Friday, 27 November, 2009 7:46:44
> > Subject: Re: [ddlm-group] Space as a list item separator
> >
> >
> >
> >
> > On 27/11/09 2:32 PM, "James Hester" <jamesrhester@gmail.com> wrote:
> >
> > > See comments below:
> > >
> > > On Fri, Nov 27, 2009 at 3:09 PM, Nick Spadaccini <nick@csse.uwa.edu.au>
> > wrote:
> > >> Timely email, come in just after the one I sent.
> > >>
> > >> My position is if we specify the syntax then we encourage its correct
> use
> > but
> > >> acknowledge that there may be cases where one might be able to recover
> > >> intent. But I wouldn?t encourage those cases.
> > >
> > > Absolutely, which is why I would like to elevate space-separated list
> > items to
> > > be correct syntax rather than 'wrong but intent is clear' syntax.
> > >>
> > >> You could say that token separator in lists are a or b or c, but that
> > just
> > >> adds a level of complexity for very little gain. The choice of comma
> > makes it
> > >> seamless to translate from the raw CIF data straight in to most
> language
> > >> specific data declaration. The only language I know that accepts one or
> > the
> > >> other or both is MatLab.
> > >
> > > Re ease of translation: you speak as if a viable approach to a CIF data
> > file
> > > is to take whole text chunks and throw them at some language
> interpreter,
> > > without doing your own parse.  Quite apart from being a rather unlikely
> > > approach, this is impossible, as without parsing you won't know where
> the
> > list
> > > finishes.  If you do do your own parse, you can populate your
> > datastructures
> > > directly during the parse, and what list separator was originally used
> in
> > the
> > > data file is completely irrelevant.
> > >
> > > Re complexity: not sure how you are planning to deal with whitespace in
> > the
> > > formal grammar, but consider the following, where I have assumed that
> each
> > > token 'eats up' the following whitespace.
> > >
> > > <dataitem> = <dataname><whitespace>+<datavalue>
> > > <datavalue> = {<list>|<string>}<whitespace>+
> > > <listdatavalue> = {<list>|<string>}<whitespace>*
> > > <list> = '[' <whitespace>* {<listdatavalue>
> > > {<comma><whitespace>*<listdatavalue>}*}* ']'
> > >
> > > If we make comma or whitespace possible separators, the last production
> > > becomes:
> > > <list> =  '[' <whitespace>* {<listdatavalue> {<comma or
> > > whitespace><listdatavalue>}*}* ']'
> > >
> > > This looks like no extra complexity, and from a user's point of view
> > > whitespace as an alternative separator is simple to understand and
> > consistent
> > > with space as a token separator used everywhere else in CIF.  Anyway, if
> > > reduction of grammar complexity is your goal, you can just completely
> > exclude
> > > commas as list separators!
> >
> > Why not? Make them spaces only, and you become consistent across the
> board.
> > I have to think about the possibility of pathological cases where spaces
> > won't work. I can't think of any at the moment.
> >
> > >
> > > Some questions about how commas behave:
> > > 1: is a trailing comma e.g. [1,2,3,4,] a syntax error?
> > > 2. are two commas in a row a syntax error? E.g. [1,2,3,,4]
> >
> > I would say yes to syntax error. I an easily determine they may need to be
> > an additional list value, but can't determine what.
> >
> > > Note the above productions assume that the answer to both is yes.
> > >
> > >>
> > >> What big advantage to a language is there to specify you can use a
> comma
> > or
> > >> whitespace as a token separator? Will you be happy with the first
> person
> > who
> > >> interprets this as being ok
> > >>
> > >> loop_
> > >>   _severalvalues 1,2,3,4,5,6,7 # these being the 7 values of
> > severalvalues
> > >>
> > > Note sure what you are getting at here: I am proposing the following:
> > >
> > > _nicelist      [1 2 3 4 5 6 7]
> > >
> > > being the same as
> > >
> > > _nicelist      [1,2,3,4,5,6,7]
> > >
> > >  Don't see how this relates to loops.
> >
> > The point was, once you say a space and comma are equivalent token
> > separators then will it be an interpretation that they are always so even
> in
> > loops? My example was not a list, just 7 values that were separated by
> > commas not spaces.
> >
> > >
> > > James.
> > > ------
> > >>
> > >> On 27/11/09 11:41 AM, "James Hester" <jamesrhester@gmail.com
> > >> <http://jamesrhester@gmail.com> > wrote:
> > >>
> > >>> Dear All: looking over the list I posted previously of items left to
> > >>> resolve, I see only one serious one outstanding: whether or not to
> allow
> > >>> space as a separator between list items.  Nick has stated:
> > >>>
> > >>> " I will propose it has to be a comma, but make the coercion rule that
> > space
> > >>> separated values in a list-type object be coerced into comma separated
> > >>> values. That is, read spaces as you want, but don't encourage them."
> > >>>
> > >>> I would like to counter-propose, as Joe did originally, that
> whitespace
> > be
> > >>> elevated to equal status with comma as a valid list separator.  I see
> no
> > >>> downside to this.  Would anyone else like to speak to this issue
> before
> > we
> > >>> vote?  In particular, I would be interested to hear why Nick doesn't
> > want to
> > >>> encourage spaces.
> > >>
> > >> cheers
> > >>
> > >> Nick
> > >>
> > >> --------------------------------
> > >> Associate Professor N. Spadaccini, PhD
> > >> School of Computer Science & Software Engineering
> > >>
> > >> The University of Western Australia    t: +61 (0)8 6488 3452
> > >> 35 Stirling Highway                    f: +61 (0)8 6488 1089
> > >> CRAWLEY, Perth,  WA  6009 AUSTRALIA   w3: www.csse.uwa.edu.au/~nick
> > >> <http://www.csse.uwa.edu.au/%7Enick>
> > >> MBDP  M002
> > >>
> > >> CRICOS Provider Code: 00126G
> > >>
> > >> e: Nick.Spadaccini@uwa.edu.au <http://Nick.Spadaccini@uwa.edu.au>
> > >>
> > >>
> > >>
> > >> _______________________________________________
> > >> ddlm-group mailing list
> > >> ddlm-group@iucr.org
> > >> http://scripts.iucr.org/mailman/listinfo/ddlm-group
> > >>
> > >
> > >
> >
> > cheers
> >
> > Nick
> >
> > --------------------------------
> > Associate Professor N. Spadaccini, PhD
> > School of Computer Science & Software Engineering
> >
> > The University of Western Australia    t: +61 (0)8 6488 3452
> > 35 Stirling Highway                    f: +61 (0)8 6488 1089
> > CRAWLEY, Perth,  WA  6009 AUSTRALIA  w3: www.csse.uwa.edu.au/~nick
> > MBDP  M002
> >
> > CRICOS Provider Code: 00126G
> >
> > e: Nick.Spadaccini@uwa.edu.au
> >
> >
> >
> >
> > _______________________________________________
> > ddlm-group mailing list
> > ddlm-group@iucr.org
> > http://scripts.iucr.org/mailman/listinfo/ddlm-group
> >
> >
> 
>
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