Subject: Re: char-upcase settable? From: Erik Naggum <erik@naggum.no> Date: 1996/08/23 Newsgroups: comp.lang.lisp Message-ID: <3049801031853023@arcana.naggum.no> Barry Margolin correctly observes that case correspondence is an attribute of a particular character repertoire, but support for multiple repertoires (at run-time) will have to handle dynamic changes to the mapping for the non-ASCII characters of, e.g., ISO 8859-1 and ISO 8859-6. Lisp systems that do not support more than ASCII may still want to allow the programmer or user(!) to employ a larger character set as the default character set; at one level or another, the case mappings will need to be changed. seeing no other means to change the case-mapping tables, `(setf char-upcase)' was my primary choice, and thus the question of conformance arose. (ANSI X3.226 clause 13.1.10 Documentation of Implementation-Defined Scripts goes to great lengths to define what a system must document that it does with additional scripts. however, this is all `implementation-defined' and would require `char-upcase' and friends to accept subtypes of character, which they are not required to do (that's a problem). this _sounds_ good, if implemented, but since one may want to use a script different from ASCII as the primary character set, a system must have thought about this _very_ carefully to get it right. the basics are right in Common Lisp (unlike all other language standards I know), but without sufficient information to get it right in practice. I'm therefore trying to get by with insufficient implementations. if anybody has given thought to the subclassing the type CHARACTER, I'd love to talk with them.) #\Erik -- and there I was, barking up the wrong cons