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[ddlm-group] Searching for a compromise on eliding
- To: ddlm-group <ddlm-group@iucr.org>
- Subject: [ddlm-group] Searching for a compromise on eliding
- From: James Hester <jamesrhester@gmail.com>
- Date: Fri, 25 Feb 2011 13:50:59 +1100
Dear DDLm-group, I think we have all had a decent chance to argue our case for Proposals P, F and F'. I have also been in small side discussions with Ralf and John W. Their points of view can be summarised as follows: (i) Behaviour of triple-quoted strings will be too confusing unless Python behaviour is followed (Ralf) (ii) There is considerable criticism of CIF in the macromolecular community because of idiosyncratic behaviour, particularly concerning quoting. We should therefore stick to accepted standards as much as possible (John W) For John W and Ralf these points outweigh any of the disadvantages of Proposal P, and so Proposal P remains their first choice. Proposal P is therefore the first choice of 3 out of 5 COMCIFS voters, and the last choice of the other two (I would rank it worse than doing nothing, actually). I note that non-voting members are uniformly opposed to Proposal P. I therefore want to try to seek some common middle ground in the hope that I can find a proposal that could be at least as acceptable as Proposal P to Ralf and/or Herbert and/or John W. Consider the following four new proposals - P-prime, Q, G and null: * Proposal P-prime: triple-quoted strings are treated as for Python 2.7. No Unicode or raw strings are defined (ie no strings starting u""" or r"""). I interpret John W and Ralf's position to be that they would be able to support this proposal as the preferred choice, as our syntax would still be entirely consistent with Python. This proposal is a considerable improvement on Proposal P, because the dangers of raw strings are taken out of the equation, and the Unicode database is no longer a dependency. We are still left with a whole bunch of (frankly pointless) elides, leading to Proposal Q: * Proposal Q: As for Proposal P-prime, with the following changes: (1) Only <backslash><delimiter> and <backslash><backslash> when it precedes <backslash><delimiter> are recognised escape sequences at the syntactical level (2) A DDLm string type, e.g. "CText", is defined in com_val.dic for which the remaining escape sequences have the meaning assigned to them by the Python 2.7 standard. mmCIF and related domains can standardise their definitions on this string type and derivatives, making the above division between syntax and dictionary invisible to users and programmers in their domain. * Proposal G: Proposal F', but with a different delimiter Ralf has indicated that he actually thinks Proposal F' is best, but only if the delimiters are not going to be confused with Python delimiters. I interpret John W's position to be that he would not support such a change in delimiters as that would simply make CIF even more idiosyncratic. Anyway, any such replacement delimiter would need to be multi-character, easy to type and unlikely to occur as the first characters in CIF1 datavalues. We would also need to reduce the characterset of non-delimited CIF2 strings to exclude any such delimiters. Ideas? * Null proposal: do nothing as we can't agree I think I could support Proposal Q as an acceptable fallback from F', and if somebody can find sensible delimiters for Proposal G that works for me as well. The preferred treatment for backslash rich text for Proposals P,P' and Q will necessarily be semicolon-delimited strings. James. -- 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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