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Re: [ddlm-group] Use of elides in strings
- To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
- Subject: Re: [ddlm-group] Use of elides in strings
- From: "Herbert J. Bernstein" <yaya@bernstein-plus-sons.com>
- Date: Fri, 20 Nov 2009 14:44:57 -0500 (EST)
- In-Reply-To: <4B06DEAF.4070109@niehs.nih.gov>
- References: <C72C423A.12515%nick@csse.uwa.edu.au><4B06DEAF.4070109@niehs.nih.gov>
Dear Colelagues, There is a difference between what are useful utitlties to have in an API in support of CIF2 and what is formally part of the base CIF2. I am all in favor of utiltities to apply and unapply the various uses for the reverse solidus -- one for cleaning up python-style use, one to handle the IUCr special characters, one for line folding, etc., but I don;t think that means we have to make one of those particular uses formally part of the base CIF2. 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, 20 Nov 2009, Joe Krahn wrote: > Unlike others here, I feel that a proper text archive library should be > able to take any string from the calling application, and return that > exact same string when reading it back in. It is the job of the archive > format to avoid delimiter problems. An applications should be able to > store and retrieve strings without such worries, and interface to an SQL > database the same is it would interface to CIF. All commonly used > database libraries work this way. Why should CIF continue to take an > archaic approach? > > I essentially agree with the design below, except that the library > should handle insertion and removal of the reverse solidus for the > limited cases where it is required. > > If it is the client application's responsibility to deal with reverse > solidus escape sequences, then the description below doesn't make sense. > In that case, the reverse solidus never has any special meaning to CIF2. > Instead, CIF2 simply disallows certain character sequences. A client > application can use whatever it wants to encode/decode the disallowed > character sequences. > > The advantage of having well-defined escape sequences at the I/O library > level is that updates to the format do not require updates to client > applications. A CIF client application should be able to send a string > to the CIF library, and not have to know in advance what CIF revision is > in use, or whether the string is semicolong block quoted or triple > quoted. By requiring the client to escape invalid sequences, the client > will have to escape strings differently, i.e. triple quote is OK withing > semi-colon quotes, and a leading semicolon is OK within triple quotes, > but not the other way around. > > Joe Krahn > > > Nick Spadaccini wrote: >> >> SUMMARISING. >> >> (a) The contents of delimited strings are returned as raw, with the token >> delimiters removed. >> (b) Where a delimiter character is to be part of the string, that character >> must be preceded by a reverse solidus when written out to the file. When >> read, any reverse solidus preceding a terminating character is deleted. >> (c) It is the responsibility of the writing and reading application to >> insert and remove the reverse solidus preceding the terminating character. >> (d) Otherwise the presence of a reverse solidus in the string has no >> meaning. > _______________________________________________ > ddlm-group mailing list > ddlm-group@iucr.org > http://scripts.iucr.org/mailman/listinfo/ddlm-group > _______________________________________________ ddlm-group mailing list ddlm-group@iucr.org http://scripts.iucr.org/mailman/listinfo/ddlm-group
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