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Re: [ddlm-group] Managing deprecation in DDLm

On 4/27/17 9:11 PM, James Hester wrote:> Dear DDLm-group,>> In the case of direct dataname equivalents, '_alias.deprecation_date' is suitable as a way of flagging deprecation.  However, if> there is no one-for-one substitution, there is no easy way to deal with deprecation. For example, on the cif_core discussion list we> have been talking about how to deprecate _cell_symmetry_setting, which has no direct equivalent in the new core dictionary.  Having> no equivalent clearly requires that we keep the dataname in the dictionary in order to interpret legacy files. For such definitions,> it would be good to (i) have an attribute that directly flags deprecation (ii) where an algorithm exists to convert values to an> alternative dataname (e.g. unit conversion), that this algorithm could be specified. While such deprecation happens very rarely, it> would seem prudent to allow for occasional mistakes in dataname definition.>> Note that in DDL2 the _item_related.function_code dataname has values that indicate deprecation (Vol G table and conversion> by multiplication: "replaces", "replacedby", "conversion_constant", "conversion_arbitrary".  This is not a particularly good match> for us, as simple replacement is already accomplished by aliases, and simple constant multiplication is not always sufficient.  We> also have dREL at our disposal for describing arbitrary transformations.>Aliases as used in DDL2 provide correspondences for semantically identical items.  The role replaces/replacedby is identifycases of deprecation and/or preferred usage which seems to be what you are seeking to represent.
> I propose the following:> (i) a new DDLm attribute '_definition.replaced_by' which would have the value of a dataname that should be used instead (or default> value 'None').> (ii) a new DDLm '_method.purpose' tag 'FromDeprecated' which could be used in the definition of the dataname that replaces the> deprecated definition. The method associated with this purpose would calculate the value of the new dataname from the old dataname> (and any other datanames that are necessary).>> Does this scheme seem reasonable to you?  If so, I will work up a proper definition.>> all the best,> 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://mailman.iucr.org/cgi-bin/mailman/listinfo/ddlm-group>
-- John Westbrook, Ph.D.RCSB, Protein Data BankRutgers, The State University of New JerseyDepartment of Chemistry and Chemical Biology174 Frelinghuysen RdPiscataway, NJ 08854-8087e-mail: john.westbrook@rcsb.orgPh: (848) 445-4290 Fax: (732) 445-4320_______________________________________________ddlm-group mailing listddlm-group@iucr.orghttp://mailman.iucr.org/cgi-bin/mailman/listinfo/ddlm-group

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