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Re: [ddlm-group] Straw poll results
- To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
- Subject: Re: [ddlm-group] Straw poll results
- From: James Hester <jamesrhester@gmail.com>
- Date: Wed, 14 Oct 2009 15:09:15 +0300
- In-Reply-To: <622678.66308.qm@web87015.mail.ird.yahoo.com>
- References: <279aad2a0910130827h34774cfey78af132620cf6f74@mail.gmail.com><20091014093413.GB4150@emerald.iucr.org><622678.66308.qm@web87015.mail.ird.yahoo.com>
Dear All, In this email I address the whole deprecation issue. Nick: perhaps you missed it, but the straw poll went in favour of immediately setting a standard, with no deprecation, so the issue of deprecation is now somewhat academic. That new standard looks almost exactly like you proposed, except for the addition of UTF8 and remaining doubts around whitespace. For the record, when proposing deprecation I envisioned a 1.2 standard which looked like 1.1 except for the addition of brackets and triple quoted strings -i.e. with only those changes that broke readers. At the same time as 1.2 was fixed, we also fix a 1.3 standard which contains the additional changes that break writers, i.e. reduced character set for non-delimited strings and removing embedded delimiters. In the notes to the 1.2 standard and in the notes on the 1.1 standard, we insert statements to the effect that the 1.1 character set for non-delimited strings is deprecated and that all new applications should use the productions contained in the 1.3 standard. That is what I meant by deprecation: formal statements attached to the standard stating that certain features are deprecated. Of course the BNF for each standard cannot communicate this information. The purpose of this deprecation was to try to shepherd the CIF-writing software community with us as we change the standard, by giving them fair warning and, when the 1.3 standard comes into effect, hopefully having a large body of conformant CIF1.3-writing software available. However, the downside is that we have two new syntax standards instead of one and increased potential for confusion, and in any case there will be plenty of CIF1.1 files floating around from archives and the consequent need to deal with them. I believe Brian's proposal of making a single, clean, maximally disruptive change to the standard and mandating a compulsory CIF1.2 header is therefore more reasonable. It is entirely in the community's hands as to when and if they make a transition to CIF1.2, and rather than pushing and pulling them as I was envisioning, we rely solely on making CIF1.2 easy to transition to (documentation, test suites) and attractive as well (dREL, UTF8), without any hint of coercion. We insert deprecation notes into the CIF1.1 standard, and explain how to write a CIF1.1 file that is also conformant to CIF1.2. That way, any new CIF writing software should at least meet the new standard. We provide simple guides on the differences for parsers and actively engage major CIF writing software packages. The only suggestion I would make is that the new syntax is called CIF2.0, in recognition of its disruptive nature. -- T +61 (02) 9717 9907 F +61 (02) 9717 3145 M +61 (04) 0249 4148 _______________________________________________ ddlm-group mailing list ddlm-group@iucr.org http://scripts.iucr.org/mailman/listinfo/ddlm-group
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