X-Git-Url: https://git.distorted.org.uk/~mdw/lisp/blobdiff_plain/920d2b95c4445a3bc1335634d0004b63148a028c..2b525992937f759211ea42e6e6f2bf0e695de96c:/mdw-mop.lisp diff --git a/mdw-mop.lisp b/mdw-mop.lisp index 92c164f..e744fcd 100644 --- a/mdw-mop.lisp +++ b/mdw-mop.lisp @@ -13,12 +13,12 @@ ;;; it under the terms of the GNU General Public License as published by ;;; the Free Software Foundation; either version 2 of the License, or ;;; (at your option) any later version. -;;; +;;; ;;; This program is distributed in the hope that it will be useful, ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;;; GNU General Public License for more details. -;;; +;;; ;;; You should have received a copy of the GNU General Public License ;;; along with this program; if not, write to the Free Software Foundation, ;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. @@ -27,20 +27,116 @@ ;;; Packages. (defpackage #:mdw.mop - (:use #:common-lisp #+cmu #:pcl) - (:export #:compatible-class + (:use #:common-lisp #:mdw.base + #+(or cmu clisp) #:mop + #+sbcl #:sb-mop + #+ecl #:clos) + (:export #:copy-instance #:copy-instance-using-class + #:with-slot-variables + #:compatible-class #:initargs-for-effective-slot #:make-effective-slot #:filtered-slot-class-mixin #:filtered-direct-slot-definition #:filtered-effective-slot-definition #:predicate-class-mixin #:abstract-class-mixin #:instantiate-abstract-class - #:mdw-class #:abstract-class + #:singleton-class-mixin + #:mdw-class #:abstract-class #:singleton-class #:print-object-with-slots)) (in-package #:mdw.mop) ;;;-------------------------------------------------------------------------- +;;; Copying instances. + +(defgeneric copy-instance-using-class (class object &rest initargs) + (:documentation + "Does the donkey-work behind copy-instance.")) + +(defmethod copy-instance-using-class + ((class standard-class) object &rest initargs) + (let ((new (apply #'allocate-instance class initargs))) + (dolist (slot (class-slots class)) + (setf (slot-value-using-class class new slot) + (slot-value-using-class class object slot))) + (apply #'shared-initialize new nil initargs) + new)) + +(defun copy-instance (object &rest initargs) + "Make a copy of OBJECT, modifying it by setting slots as requested by + INITARGS." + (apply #'copy-instance-using-class (class-of object) object initargs)) + +;;;-------------------------------------------------------------------------- +;;; Handy macros. + +(defmacro with-slot-variables (slots instance &body body) + "A copy-out-and-write-back variant of with-slots. + + The SLOTS argument is a list of slot specifications, each of which has the + form (NAME &key :update :variable). VARIABLE defaults to NAME, and + :update defaults to nil. + + The INSTANCE argument has the form (INSTANCE &key :class), but an atom may + be used in place of a singleton list. If the CLASS is specified, then two + good things happen: firstly the INSTANCE is declared to be a member of the + CLASS, and secondly all the slot variables are declared to have the + appropriate types, as dredged up from the class's effective slot + definitions. + + The effect of all this is to return the result of evaluating BODY in an + environment where the VARIABLEs are bound to the values of the NAMEd slots + of the given INSTANCE. If BODY completes successfully (rather than + throwing out, restarting, or anything like that) then the final values of + VARIABLEs for which UPDATE was set non-nil are written back to their + corresponding slots. + + This stands a good chance of being rather faster than with-slots. It + does, however, run the risk of leaving things in an inconsistent state if + BODY escapes half-way through. Also, this requires recompilation if a + class's slots change type." + (multiple-value-bind (instance class) + (destructuring-bind + (instance &key class) + (listify instance) + (values instance (and class (find-class class)))) + (let ((slots (mapcar (lambda (slot) + (destructuring-bind + (name &key update (variable name)) + (listify slot) + (list name variable update))) + (if slots + (listify slots) + (mapcar #'slot-definition-name + (class-slots class)))))) + (with-parsed-body (body decls) body + (with-gensyms (instvar) + `(let ((,instvar ,instance)) + ,@(and class `((declare (type ,(class-name class) ,instvar)))) + (let ,(loop for (name var update) in slots + collect `(,var (slot-value ,instvar ',name))) + ,@(and class + `((declare + ,@(loop + for (name var update) in slots + for slot = (or (find name + (class-slots class) + :key #'slot-definition-name) + (error + "Slot ~S not found in class ~S." + name (class-name class))) + collect `(type + ,(slot-definition-type slot) + ,name))))) + ,@decls + (multiple-value-prog1 + (progn ,@body) + ,@(loop for (name var update) in slots + when update + collect `(setf (slot-value ,instvar ',name) + ,var)))))))))) + +;;;-------------------------------------------------------------------------- ;;; Basic stuff. (defclass compatible-class (standard-class) @@ -100,6 +196,7 @@ (defmethod compute-effective-slot-definition ((class compatible-class) slot-name direct-slots) "Construct an effective slot definition for the given slot." + (declare (ignore slot-name)) ;; ;; Ideally we don't want to mess with a slot if it's entirely handled by ;; the implementation. This check seems to work OK. @@ -124,13 +221,13 @@ (Yes, I know that using functions would be nicer, but the MOP makes that surprisingly difficult.)")) +(defgeneric slot-definition-filter (slot) + (:method ((slot slot-definition)) nil)) + (defclass filtered-direct-slot-definition (standard-direct-slot-definition) ((filter :initarg :filter :reader slot-definition-filter))) -(defgeneric slot-definition-filter (slot) - (:method ((slot slot-definition)) nil)) - (defclass filtered-effective-slot-definition (standard-effective-slot-definition) ((filter :initarg :filter :accessor slot-definition-filter))) @@ -234,6 +331,22 @@ (error 'instantiate-abstract-class :class class)) ;;;-------------------------------------------------------------------------- +;;; Singleton classes. + +(defclass singleton-class-mixin (compatible-class) + ((instance :initform nil :type (or null standard-object))) + (:documentation + "A class which has only one instance. All calls to `make-instance' return + the same object.")) + +(defmethod allocate-instance ((class singleton-class-mixin) &key) + "If the class already has an instance, return it; otherwise allocate one, + store it away, and return that." + (with-slots (instance) class + (or instance + (setf instance (call-next-method))))) + +;;;-------------------------------------------------------------------------- ;;; Useful classes. (defclass mdw-class (filtered-slot-class-mixin @@ -247,34 +360,35 @@ features.")) (defclass abstract-class (mdw-class abstract-class-mixin) ()) +(defclass singleton-class (mdw-class singleton-class-mixin) ()) ;;;-------------------------------------------------------------------------- ;;; Printing things. (defun print-object-with-slots (obj stream) "Prints objects in a pleasant way. Not too clever about circularity." - (let ((class (pcl:class-of obj)) - (magic (cons 'magic nil))) + (let ((class (class-of obj)) + (magic (cons 'magic nil))) (print-unreadable-object (obj stream) (pprint-logical-block - (stream - (mapcan (lambda (slot) - (list (or (car (slot-definition-initargs slot)) - (slot-definition-name slot)) - (if (slot-boundp-using-class class obj slot) - (slot-value-using-class class obj slot) - magic))) - (pcl:class-slots class))) - (format stream "~S" (pcl:class-name class)) - (let ((sep nil)) - (loop - (pprint-exit-if-list-exhausted) - (if sep - (format stream " ~_") - (progn (format stream " ~@_~:I") (setf sep t))) - (let ((name (pprint-pop)) - (value (pprint-pop))) - (format stream "~S ~@_~:[~S~;~*~]" - name (eq value magic) value)))))))) + (stream + (mapcan (lambda (slot) + (list (or (car (slot-definition-initargs slot)) + (slot-definition-name slot)) + (if (slot-boundp-using-class class obj slot) + (slot-value-using-class class obj slot) + magic))) + (class-slots class))) + (format stream "~S" (class-name class)) + (let ((sep nil)) + (loop + (pprint-exit-if-list-exhausted) + (if sep + (format stream " ~_") + (progn (format stream " ~@_~:I") (setf sep t))) + (let ((name (pprint-pop)) + (value (pprint-pop))) + (format stream "~S ~@_~:[~W~;#~*~]" + name (eq value magic) value)))))))) ;;;----- That's all, folks --------------------------------------------------