Update of /project/mcclim/cvsroot/mcclim/Extensions/conditional-commands
In directory common-lisp.net:/tmp/cvs-serv13488
Modified Files:
creating-assoc.lisp
Log Message:
Remove the old and uncommented versions of CREATING-ASSOC.
Date: Thu Nov 24 19:37:12 2005
Author: mretzlaff
Index: mcclim/Extensions/conditional-commands/creating-assoc.lisp
diff -u mcclim/Extensions/conditional-commands/creating-assoc.lisp:1.1 mcclim/Extensions/conditional-commands/creating-assoc.lisp:1.2
--- mcclim/Extensions/conditional-commands/creating-assoc.lisp:1.1 Thu Nov 24 19:35:34 2005
+++ mcclim/Extensions/conditional-commands/creating-assoc.lisp Thu Nov 24 19:37:12 2005
@@ -1,80 +1,5 @@
(in-package :creating-assoc)
-;;; Doesn't work:
-;;;
-;;; (defun creating-assoc (item alist)
-;;; "assoc that creates the requested alist item on-the-fly if not yet existing"
-;;; (let ((item-assoc (assoc item alist)))
-;;; (unless item-assoc
-;;; (let ((new-item (list item)))
-;;; (push new-item alist)
-;;; (setf item-assoc new-item)))))
-
-;;; Doesn't work:
-;;;
-;;; (defmacro creating-assoc (item alist)
-;;; "assoc that creates the requested alist item on-the-fly if not yet existing"
-;;; (let ((entry (gensym "entry-"))
-;;; (new-item (gensym "new-item-"))
-;;; (the-item (gensym "the-item-"))
-;;; (the-alist (gensym "the-alist-")))
-;;; `(let* ((,the-item ,item)
-;;; (,the-alist ,alist)
-;;; (,entry (assoc ,the-item ,the-alist)))
-;;; (unless ,entry
-;;; (let ((,new-item (list ,the-item)))
-;;; (push ,new-item ,the-alist)
-;;; (setf ,entry ,new-item))))))
-
-;;; Does work, but ALIST will be evaluated twice:
-;;;
-;;; (defmacro creating-assoc (item alist)
-;;; "assoc that creates the requested alist item on-the-fly if not yet existing"
-;;; (let ((entry (gensym "entry-"))
-;;; (new-item (gensym "new-item-"))
-;;; (the-item (gensym "the-item-")))
-;;; `(let* ((,the-item ,item)
-;;; (,entry (assoc ,the-item ,alist)))
-;;; (unless ,entry
-;;; (let ((,new-item (list ,the-item)))
-;;; (push ,new-item ,alist)
-;;; (setf ,entry ,new-item))))))
-
-;;; From SBCL source, uses GET-SETF-METHOD, a relic from pre-ANSI Common Lisp:
-;;;
-;;; (defmacro-mundanely push (obj place &environment env)
-;;; #!+sb-doc
-;;; "Takes an object and a location holding a list. Conses the object onto
-;;; the list, returning the modified list. OBJ is evaluated before PLACE."
-;;; (multiple-value-bind (dummies vals newval setter getter)
-;;; (get-setf-method place env)
-;;; (let ((g (gensym)))
-;;; `(let* ((,g ,obj)
-;;; ,@(mapcar #'list dummies vals)
-;;; (,(car newval) (cons ,g ,getter)))
-;;; ,setter))))
-
-;;; Example CLHS page on GET-SETF-EXPANSION:
-;;; (Notice that there is an error, "(if (cdr new)" should be replaced by "(if (cdr ,(car new))".)
-;;;
-;;; (defmacro xpop (place &environment env)
-;;; (multiple-value-bind (dummies vals new setter getter)
-;;; (get-setf-expansion place env)
-;;; `(let* (,@(mapcar #'list dummies vals) (,(car new) ,getter))
-;;; (if (cdr new) (error "Can't expand this."))
-;;; (prog1 (car ,(car new))
-;;; (setq ,(car new) (cdr ,(car new)))
-;;; ,setter))))
-
-;;; New version, still does not work:
-;;;
-;;; (defun creating-assoc (item alist)
-;;; "assoc that creates the requested alist item on-the-fly if not yet existing"
-;;; (or (assoc item alist)
-;;; (first (push (list item) alist))))
-
-;;; Macro based on the new (not-working) defun, works and is nice:
-;;;
(defmacro creating-assoc (item alist &environment env)
"assoc that creates the requested alist item on-the-fly if not yet existing"
(multiple-value-bind (dummies vals new setter getter)