Re: [ddlm-group] Proposal to enhance the behaviour of a DDLm "Set"category: please consider

Dear all,

Comments below:

On Sunday, June 05, 2016 11:58 PM, James Hester wrote:

> [...] The real issue is a live one even for a straight relational database, i.e. if you add a key column to a table, how do you tell all the applications using that table to pay attention to the value of the new key?
>
> [...] No harm arises for legacy software dealing with legacy files, or future software dealing with any file. There is potential harm for legacy CIF-reading software dealing with new-style files.  This is something we have to face and find a solution for.
>
> [...]Unfortunately my original proposal does introduce further equivalent datanames, which I think must be avoided [...].  Our best hope is therefore likely to be something very similar to John B's proposal, which is really a description of what you do in imgCIF.

I don't see how there can be a solution that simultaneously satisfies all the criteria that have been offered.  If we refuse to permit existing data names to be used in ways that existing software might not anticipate, and we refuse to introduce new data names for alternative uses of the same entities, then for entities we have already defined, we are forever stuck with uses that can be accommodated by their original definitions.  If we're not satisfied with that outcome then the only way I see forward is to reject one of the criteria.


John

________________________________

Email Disclaimer: www.stjude.org/emaildisclaimer
Consultation Disclaimer: www.stjude.org/consultationdisclaimer
_______________________________________________
ddlm-group mailing list
ddlm-group@iucr.org
http://mailman.iucr.org/cgi-bin/mailman/listinfo/ddlm-group