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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: It is okay for things to break in the future!
 On Mon, 2022-09-05 at 19:46 +0100, Norman Gray wrote: > > Fine -- then where I said '12', read 'up to 15' (which Wikipedia > suggests is the ITU maximum). And Wikipedia is never wrong. Although i gave a longer example earlier in the thread, which also contained (necessary) alphabetic characters. > The original point is not phone numbers, or about validation, but > the general point about a hard-coded maximum length not necessarily > being bad design. But you were willing to use 12 digits, which would exclude some legitimate values. If the purpose is to store telephone numbers and be standards compliant and not be blamed, go ahead, you found a standard that lets you use 12 digits. If the goal is to enable users of the database to contact someone by telephone, and they say you need to dial extension 3056, wait for the dial tone, press star and dial 23#, then if you don't record that you might as well not record a number at all. And no, it's not at all unheard of for contacting people to work like that. Even dial strings for accoustic modems supported that sort of use case, by the way. The wider point is emphasized here - is the goal to be useful and pragmatic, or is it to reject values that some putative softwware can't handle? It depends on the context. If the 'phone number (to continue the example) is to be used exclusively by computer, and you know that your autodialer can only handle 12 digits, do you store the additional information for the time when you get a new autodialer, or do you discard the data and pay the price later? The "lex" lexical analyzer generator used to generate code that read input a line at a time, with a 200 character line length limit; longer lines caused a crash at runtime. I think it's easy to argue convincingly this was unhelpful: general tools can't predict the context in which they will be used, so should not have limits. Years ago, an automobile rescue organisation in the UK used to record in a database the instructions to get to someone who had broken down, based on their verbal instructions. Many years later they were able to use this data to make public their program that gave directions in the way a human had - "take the right-hand fork in the road at the windmill in Saxtead, ignoring the sign, and turn left just past the big pub" that was incredibly useful - until "satnav" replaced it and sent everyone into the mill pond in Earl Soham instead - faulty data suddenly started to matter in new ways. -- Liam Quin, https://www.delightfulcomputing.com/ Available for XML/Document/Information Architecture/XSLT/ XSL/XQuery/Web/Text Processing/A11Y training, work & consulting. Barefoot Web-slave, antique illustrations: http://www.fromoldbooks.org 
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