[QUERY] Support Unicode escapes in the Lisp reader, à la Java

QUERY 2006-04-16 Aidan Kehoe <kehoea(a)parhasard.net&gt; * lispref/objects.texi (Character Type): Describe support for ?\u and ?\U as character escapes allowing you to specify the Unicode code point of a character. What is the purpose of having two syntaxes? I would prefer a single syntax, ?\U<HEXDIGIT>+, with an error being signaled if the "character" can't be represented in that XEmacs. Also, I think permitting elision of leading zeros is false convenience. You rarely see TWO-digit octal constants, even in syntaxes where they are permitted. I think the same will happen here; ie, you'll typically see ?\U000A for linefeed, if people are going to use that syntax at all. We should use the same syntax in strings as we do in characters, and in that case requiring four hexdigits will be easier to read and to write code for. (I guess in that case it makes sense to have two syntaxes, since we do need to provide for Planes 1-16, but writing 8 digits 99% of the time would be unbearable.) I question the need for this at the present time, as code using this escape would necessarily be incompatible with 21.4. I would prefer introducing these syntaxes for character constants when we convert the Lisp library source encoding to Unicode. -- School of Systems and Information Engineering http://turnbull.sk.tsukuba.ac.jp University of Tsukuba Tennodai 1-1-1 Tsukuba 305-8573 JAPAN Ask not how you can "do" free software business; ask what your business can "do for" free software.