Subject: Re: (setf (readtable-case *readtable*) :invert) completely preserves symbol case in CMUCL From: Erik Naggum <email@example.com> Date: Sun, 26 May 2002 17:42:04 GMT Newsgroups: comp.lang.lisp Message-ID: <firstname.lastname@example.org> * Adam Warner <email@example.com> | Yes I have achieved enlightenment Erik. You made my day! | I can't use preserve because none of the built in functions can be called | using lower case. Perhaps a custom compiled CMUCL image would be a long | term solution. Well, that way lies madness. One Common Lisp vendor has decided to make a "custom" world in which symbols are in their preferred lower-case. While I also like to read and see lower-case, all I need to do to get that most of the time is with either :invert or :upcase and *print-case* to :downcase. However, if you want to use lower-case names in your own code, you can shadow intern, find-symbol, and symbol-name to invert their argument. Efficient invertion is not necessarily a trivial task, and your implementation may have optimized functions for it, but this is a shot, and intended to be an efficien tone. Just how efficient it is seems to vary a lot between implementations: (defun invert-string (string) (declare (optimize (speed 3) (safety 0)) (simple-string string)) (check-type string 'string) (prog ((invert nil) (index 0) (length (length string))) (declare (simple-string invert) (type (integer 0 65536) index length)) unknown-case (cond ((= index length) (return string)) ((upper-case-p (schar string index)) (when (and (/= (1+ index) length) (lower-case-p (schar string (1+ index)))) (return string)) (setq invert (copy-seq string)) (go upper-case)) ((lower-case-p (schar string index)) (setq invert (copy-seq string)) (go lower-case)) (t (incf index) (go unknown-case))) upper-case (setf (schar invert index) (char-downcase (schar invert index))) (incf index) (cond ((= index length) (return invert)) ((lower-case-p (schar invert index)) (return string)) (t (go upper-case))) lower-case (setf (schar invert index) (char-upcase (schar invert index))) (incf index) (cond ((= index length) (return invert)) ((upper-case-p (schar invert index)) (return string)) (t (go lower-case))))) -- In a fight against something, the fight has value, victory has none. In a fight for something, the fight is a loss, victory merely relief. 70 percent of American adults do not understand the scientific process.