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Re: [ddlm-group] String concatenation operator in CIF2. .

On Thursday, October 14, 2010 7:48 AM, James Hester wrote:

>There are three separate issues: (1) do we want a string concatenation
>operator? (2) If so, what is the grammar for this operator (3) what
>character(s) will be used for this operator?


>Regarding the particular grammar of concatenation, I believe we are
>all in agreement that the concatenation operator should be separated
>by whitespace from all neighbouring tokens.  Again: unless there are
>objections soon, we can also declare the grammar for the operator to
>have been accepted.

Provided that a concatenation operator is in fact accepted into the language, I do agree that it should be separated by whitespace on both sides.

>  Incidentally, do we all agree that _item_q and
>_item_s in the following have the same value?
>_item_q        3  <concat> 4
>_item_s        34

I think there is a question as to whether that would be a well-formed CIF at all.  As I understood the proposal, the concatenation operator was applicable only to quote-delimited strings, not to whitespace-delimited ones.  I'm not sure whether it's intended to be applicable to triple-quote-delimited strings and / or text blocks.

If the concatenation operator were applicable to whitespace-delimited strings, then I agree that _item_q and _item_s in your example would have the same value.  That would be another reason to disfavor + as the operator.


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

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