X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fpcl%2Fdefcombin.lisp;h=676bf9ba00f0341c7373c3713ac4e178b4d1f4b9;hb=31f072311935e32751508ecf824905c6b58a1d95;hp=44f8fdbb5ebcc872a8a3d8361ce1eeb2c6dc3056;hpb=967a23111b5c6e7d457d879dea546ace812fc962;p=sbcl.git diff --git a/src/pcl/defcombin.lisp b/src/pcl/defcombin.lisp index 44f8fdb..676bf9b 100644 --- a/src/pcl/defcombin.lisp +++ b/src/pcl/defcombin.lisp @@ -27,11 +27,11 @@ (declare (ignore args)) `(progn (with-single-package-locked-error - (:symbol ',(second form) "defining ~A as a method combination")) + (:symbol ',(second form) "defining ~A as a method combination")) ,(if (and (cddr form) - (listp (caddr form))) - (expand-long-defcombin form) - (expand-short-defcombin form)))) + (listp (caddr form))) + (expand-long-defcombin form) + (expand-short-defcombin form)))) ;;;; standard method combination @@ -42,8 +42,8 @@ ;;; FIND-METHOD-COMBINATION must appear in this file for bootstrapping ;;; reasons. (defmethod find-method-combination ((generic-function generic-function) - (type (eql 'standard)) - options) + (type (eql 'standard)) + options) (when options (method-combination-error "The method combination type STANDARD accepts no options.")) @@ -67,38 +67,38 @@ (defun expand-short-defcombin (whole) (let* ((type (cadr whole)) - (documentation - (getf (cddr whole) :documentation "")) - (identity-with-one-arg - (getf (cddr whole) :identity-with-one-argument nil)) - (operator - (getf (cddr whole) :operator type))) + (documentation + (getf (cddr whole) :documentation "")) + (identity-with-one-arg + (getf (cddr whole) :identity-with-one-argument nil)) + (operator + (getf (cddr whole) :operator type))) `(load-short-defcombin - ',type ',operator ',identity-with-one-arg ',documentation))) + ',type ',operator ',identity-with-one-arg ',documentation + (sb-c:source-location)))) -(defun load-short-defcombin (type operator ioa doc) - (let* ((pathname *load-pathname*) - (specializers - (list (find-class 'generic-function) - (intern-eql-specializer type) - *the-class-t*)) - (old-method - (get-method #'find-method-combination () specializers nil)) - (new-method nil)) +(defun load-short-defcombin (type operator ioa doc source-location) + (let* ((specializers + (list (find-class 'generic-function) + (intern-eql-specializer type) + *the-class-t*)) + (old-method + (get-method #'find-method-combination () specializers nil)) + (new-method nil)) (setq new-method - (make-instance 'standard-method - :qualifiers () - :specializers specializers - :lambda-list '(generic-function type options) - :function (lambda (args nms &rest cm-args) - (declare (ignore nms cm-args)) - (apply - (lambda (gf type options) - (declare (ignore gf)) - (short-combine-methods - type options operator ioa new-method doc)) - args)) - :definition-source `((define-method-combination ,type) ,pathname))) + (make-instance 'standard-method + :qualifiers () + :specializers specializers + :lambda-list '(generic-function type options) + :function (lambda (args nms &rest cm-args) + (declare (ignore nms cm-args)) + (apply + (lambda (gf type options) + (declare (ignore gf)) + (short-combine-methods + type options operator ioa new-method doc)) + args)) + :definition-source source-location)) (when old-method (remove-method #'find-method-combination old-method)) (add-method #'find-method-combination new-method) @@ -107,156 +107,153 @@ (defun short-combine-methods (type options operator ioa method doc) (cond ((null options) (setq options '(:most-specific-first))) - ((equal options '(:most-specific-first))) - ((equal options '(:most-specific-last))) - (t - (method-combination-error - "Illegal options to a short method combination type.~%~ - The method combination type ~S accepts one option which~%~ - must be either :MOST-SPECIFIC-FIRST or :MOST-SPECIFIC-LAST." - type))) + ((equal options '(:most-specific-first))) + ((equal options '(:most-specific-last))) + (t + (method-combination-error + "Illegal options to a short method combination type.~%~ + The method combination type ~S accepts one option which~%~ + must be either :MOST-SPECIFIC-FIRST or :MOST-SPECIFIC-LAST." + type))) (make-instance 'short-method-combination - :type type - :options options - :operator operator - :identity-with-one-argument ioa - :definition-source method - :documentation doc)) + :type type + :options options + :operator operator + :identity-with-one-argument ioa + :definition-source method + :documentation doc)) (defmethod compute-effective-method ((generic-function generic-function) - (combin short-method-combination) - applicable-methods) + (combin short-method-combination) + applicable-methods) (let ((type (method-combination-type combin)) - (operator (short-combination-operator combin)) - (ioa (short-combination-identity-with-one-argument combin)) - (order (car (method-combination-options combin))) - (around ()) - (primary ())) + (operator (short-combination-operator combin)) + (ioa (short-combination-identity-with-one-argument combin)) + (order (car (method-combination-options combin))) + (around ()) + (primary ())) (flet ((invalid (gf combin m) - (if *in-precompute-effective-methods-p* - (return-from compute-effective-method - `(%invalid-qualifiers ',gf ',combin ',m)) - (invalid-qualifiers gf combin m)))) + (return-from compute-effective-method + `(%invalid-qualifiers ',gf ',combin ',m)))) (dolist (m applicable-methods) - (let ((qualifiers (method-qualifiers m))) - (cond ((null qualifiers) (invalid generic-function combin m)) - ((cdr qualifiers) (invalid generic-function combin m)) - ((eq (car qualifiers) :around) - (push m around)) - ((eq (car qualifiers) type) - (push m primary)) - (t (invalid generic-function combin m)))))) + (let ((qualifiers (method-qualifiers m))) + (cond ((null qualifiers) (invalid generic-function combin m)) + ((cdr qualifiers) (invalid generic-function combin m)) + ((eq (car qualifiers) :around) + (push m around)) + ((eq (car qualifiers) type) + (push m primary)) + (t (invalid generic-function combin m)))))) (setq around (nreverse around)) (ecase order (:most-specific-last) ; nothing to be done, already in correct order (:most-specific-first (setq primary (nreverse primary)))) (let ((main-method - (if (and (null (cdr primary)) - (not (null ioa))) - `(call-method ,(car primary) ()) - `(,operator ,@(mapcar (lambda (m) `(call-method ,m ())) - primary))))) + (if (and (null (cdr primary)) + (not (null ioa))) + `(call-method ,(car primary) ()) + `(,operator ,@(mapcar (lambda (m) `(call-method ,m ())) + primary))))) (cond ((null primary) - ;; As of sbcl-0.8.0.80 we don't seem to need to need - ;; to do anything messy like - ;; `(APPLY (FUNCTION (IF AROUND - ;; 'NO-PRIMARY-METHOD - ;; 'NO-APPLICABLE-METHOD) - ;; ',GENERIC-FUNCTION - ;; .ARGS.) - ;; here because (for reasons I don't understand at the - ;; moment -- WHN) control will never reach here if there - ;; are no applicable methods, but instead end up - ;; in NO-APPLICABLE-METHODS first. - ;; - ;; FIXME: The way that we arrange for .ARGS. to be bound - ;; here seems weird. We rely on EXPAND-EFFECTIVE-METHOD-FUNCTION - ;; recognizing any form whose operator is %NO-PRIMARY-METHOD - ;; as magical, and carefully surrounding it with a - ;; LAMBDA form which binds .ARGS. But... - ;; 1. That seems fragile, because the magicalness of - ;; %NO-PRIMARY-METHOD forms is scattered around - ;; the system. So it could easily be broken by - ;; locally-plausible maintenance changes like, - ;; e.g., using the APPLY expression above. - ;; 2. That seems buggy w.r.t. to MOPpish tricks in - ;; user code, e.g. - ;; (DEFMETHOD COMPUTE-EFFECTIVE-METHOD :AROUND (...) - ;; `(PROGN ,(CALL-NEXT-METHOD) (INCF *MY-CTR*))) + ;; As of sbcl-0.8.0.80 we don't seem to need to need + ;; to do anything messy like + ;; `(APPLY (FUNCTION (IF AROUND + ;; 'NO-PRIMARY-METHOD + ;; 'NO-APPLICABLE-METHOD) + ;; ',GENERIC-FUNCTION + ;; .ARGS.) + ;; here because (for reasons I don't understand at the + ;; moment -- WHN) control will never reach here if there + ;; are no applicable methods, but instead end up + ;; in NO-APPLICABLE-METHODS first. + ;; + ;; FIXME: The way that we arrange for .ARGS. to be bound + ;; here seems weird. We rely on EXPAND-EFFECTIVE-METHOD-FUNCTION + ;; recognizing any form whose operator is %NO-PRIMARY-METHOD + ;; as magical, and carefully surrounding it with a + ;; LAMBDA form which binds .ARGS. But... + ;; 1. That seems fragile, because the magicalness of + ;; %NO-PRIMARY-METHOD forms is scattered around + ;; the system. So it could easily be broken by + ;; locally-plausible maintenance changes like, + ;; e.g., using the APPLY expression above. + ;; 2. That seems buggy w.r.t. to MOPpish tricks in + ;; user code, e.g. + ;; (DEFMETHOD COMPUTE-EFFECTIVE-METHOD :AROUND (...) + ;; `(PROGN ,(CALL-NEXT-METHOD) (INCF *MY-CTR*))) `(%no-primary-method ',generic-function .args.)) - ((null around) main-method) - (t - `(call-method ,(car around) - (,@(cdr around) (make-method ,main-method)))))))) + ((null around) main-method) + (t + `(call-method ,(car around) + (,@(cdr around) (make-method ,main-method)))))))) (defmethod invalid-qualifiers ((gf generic-function) - (combin short-method-combination) - method) + (combin short-method-combination) + method) (let ((qualifiers (method-qualifiers method)) - (type (method-combination-type combin))) + (type (method-combination-type combin))) (let ((why (cond - ((null qualifiers) "has no qualifiers") - ((cdr qualifiers) "has too many qualifiers") - (t (aver (and (neq (car qualifiers) type) - (neq (car qualifiers) :around))) - "has an invalid qualifier")))) + ((null qualifiers) "has no qualifiers") + ((cdr qualifiers) "has too many qualifiers") + (t (aver (and (neq (car qualifiers) type) + (neq (car qualifiers) :around))) + "has an invalid qualifier")))) (invalid-method-error method "The method ~S on ~S ~A.~%~ - The method combination type ~S was defined with the~%~ - short form of DEFINE-METHOD-COMBINATION and so requires~%~ - all methods have either the single qualifier ~S or the~%~ - single qualifier :AROUND." + The method combination type ~S was defined with the~%~ + short form of DEFINE-METHOD-COMBINATION and so requires~%~ + all methods have either the single qualifier ~S or the~%~ + single qualifier :AROUND." method gf why type type)))) ;;;; long method combinations (defun expand-long-defcombin (form) (let ((type (cadr form)) - (lambda-list (caddr form)) - (method-group-specifiers (cadddr form)) - (body (cddddr form)) - (args-option ()) - (gf-var nil)) + (lambda-list (caddr form)) + (method-group-specifiers (cadddr form)) + (body (cddddr form)) + (args-option ()) + (gf-var nil)) (when (and (consp (car body)) (eq (caar body) :arguments)) (setq args-option (cdr (pop body)))) (when (and (consp (car body)) (eq (caar body) :generic-function)) (setq gf-var (cadr (pop body)))) (multiple-value-bind (documentation function) - (make-long-method-combination-function - type lambda-list method-group-specifiers args-option gf-var - body) + (make-long-method-combination-function + type lambda-list method-group-specifiers args-option gf-var + body) `(load-long-defcombin ',type ',documentation #',function - ',args-option)))) + ',args-option (sb-c:source-location))))) (defvar *long-method-combination-functions* (make-hash-table :test 'eq)) -(defun load-long-defcombin (type doc function args-lambda-list) +(defun load-long-defcombin (type doc function args-lambda-list source-location) (let* ((specializers - (list (find-class 'generic-function) - (intern-eql-specializer type) - *the-class-t*)) - (old-method - (get-method #'find-method-combination () specializers nil)) - (new-method - (make-instance 'standard-method - :qualifiers () - :specializers specializers - :lambda-list '(generic-function type options) - :function (lambda (args nms &rest cm-args) - (declare (ignore nms cm-args)) - (apply - (lambda (generic-function type options) - (declare (ignore generic-function)) - (make-instance 'long-method-combination - :type type - :options options - :args-lambda-list args-lambda-list - :documentation doc)) - args)) - :definition-source `((define-method-combination ,type) - ,*load-pathname*)))) + (list (find-class 'generic-function) + (intern-eql-specializer type) + *the-class-t*)) + (old-method + (get-method #'find-method-combination () specializers nil)) + (new-method + (make-instance 'standard-method + :qualifiers () + :specializers specializers + :lambda-list '(generic-function type options) + :function (lambda (args nms &rest cm-args) + (declare (ignore nms cm-args)) + (apply + (lambda (generic-function type options) + (declare (ignore generic-function)) + (make-instance 'long-method-combination + :type type + :options options + :args-lambda-list args-lambda-list + :documentation doc)) + args)) + :definition-source source-location))) (setf (gethash type *long-method-combination-functions*) function) (when old-method (remove-method #'find-method-combination old-method)) (add-method #'find-method-combination new-method) @@ -264,13 +261,13 @@ type)) (defmethod compute-effective-method ((generic-function generic-function) - (combin long-method-combination) - applicable-methods) + (combin long-method-combination) + applicable-methods) (funcall (gethash (method-combination-type combin) - *long-method-combination-functions*) - generic-function - combin - applicable-methods)) + *long-method-combination-functions*) + generic-function + combin + applicable-methods)) (defun make-long-method-combination-function (type ll method-group-specifiers args-option gf-var body) @@ -278,31 +275,31 @@ (multiple-value-bind (real-body declarations documentation) (parse-body body) (let ((wrapped-body - (wrap-method-group-specifier-bindings method-group-specifiers - declarations - real-body))) + (wrap-method-group-specifier-bindings method-group-specifiers + declarations + real-body))) (when gf-var - (push `(,gf-var .generic-function.) (cadr wrapped-body))) + (push `(,gf-var .generic-function.) (cadr wrapped-body))) (when args-option - (setq wrapped-body (deal-with-args-option wrapped-body args-option))) + (setq wrapped-body (deal-with-args-option wrapped-body args-option))) (when ll - (setq wrapped-body - `(apply #'(lambda ,ll ,wrapped-body) - (method-combination-options .method-combination.)))) + (setq wrapped-body + `(apply #'(lambda ,ll ,wrapped-body) + (method-combination-options .method-combination.)))) (values - documentation - `(lambda (.generic-function. .method-combination. .applicable-methods.) - (declare (ignorable .generic-function. - .method-combination. .applicable-methods.)) - (block .long-method-combination-function. ,wrapped-body)))))) + documentation + `(lambda (.generic-function. .method-combination. .applicable-methods.) + (declare (ignorable .generic-function. + .method-combination. .applicable-methods.)) + (block .long-method-combination-function. ,wrapped-body)))))) -(define-condition long-method-combination-error +(define-condition long-method-combination-error (reference-condition simple-error) () - (:default-initargs + (:default-initargs :references (list '(:ansi-cl :macro define-method-combination)))) ;;; NOTE: @@ -317,15 +314,15 @@ (defun group-cond-clause (name tests specializer-cache star-only) (let ((maybe-error-clause - (if star-only - `(setq ,specializer-cache .specializers.) - `(if (and (equal ,specializer-cache .specializers.) + (if star-only + `(setq ,specializer-cache .specializers.) + `(if (and (equal ,specializer-cache .specializers.) (not (null .specializers.))) (return-from .long-method-combination-function. '(error 'long-method-combination-error - :format-control "More than one method of type ~S ~ - with the same specializers." - :format-arguments (list ',name))) + :format-control "More than one method of type ~S ~ + with the same specializers." + :format-arguments (list ',name))) (setq ,specializer-cache .specializers.))))) `((or ,@tests) ,maybe-error-clause @@ -350,7 +347,7 @@ (push `(when (null ,name) (return-from .long-method-combination-function. '(error 'long-method-combination-error - :format-control "No ~S methods." + :format-control "No ~S methods." :format-arguments (list ',name)))) required-checks)) (loop (unless (and (constantp order) @@ -379,53 +376,53 @@ (defun parse-method-group-specifier (method-group-specifier) ;;(declare (values name tests description order required)) (let* ((name (pop method-group-specifier)) - (patterns ()) - (tests - (let (collect) - (block collect-tests - (loop - (if (or (null method-group-specifier) - (memq (car method-group-specifier) - '(:description :order :required))) - (return-from collect-tests t) - (let ((pattern (pop method-group-specifier))) - (push pattern patterns) - (push (parse-qualifier-pattern name pattern) + (patterns ()) + (tests + (let (collect) + (block collect-tests + (loop + (if (or (null method-group-specifier) + (memq (car method-group-specifier) + '(:description :order :required))) + (return-from collect-tests t) + (let ((pattern (pop method-group-specifier))) + (push pattern patterns) + (push (parse-qualifier-pattern name pattern) collect))))) (nreverse collect)))) (values name - tests - (getf method-group-specifier :description - (make-default-method-group-description patterns)) - (getf method-group-specifier :order :most-specific-first) - (getf method-group-specifier :required nil)))) + tests + (getf method-group-specifier :description + (make-default-method-group-description patterns)) + (getf method-group-specifier :order :most-specific-first) + (getf method-group-specifier :required nil)))) (defun parse-qualifier-pattern (name pattern) (cond ((eq pattern '()) `(null .qualifiers.)) - ((eq pattern '*) t) - ((symbolp pattern) `(,pattern .qualifiers.)) - ((listp pattern) `(qualifier-check-runtime ',pattern .qualifiers.)) - (t (error "In the method group specifier ~S,~%~ - ~S isn't a valid qualifier pattern." - name pattern)))) + ((eq pattern '*) t) + ((symbolp pattern) `(,pattern .qualifiers.)) + ((listp pattern) `(qualifier-check-runtime ',pattern .qualifiers.)) + (t (error "In the method group specifier ~S,~%~ + ~S isn't a valid qualifier pattern." + name pattern)))) (defun qualifier-check-runtime (pattern qualifiers) (loop (cond ((and (null pattern) (null qualifiers)) - (return t)) - ((eq pattern '*) (return t)) - ((and pattern qualifiers (eq (car pattern) (car qualifiers))) - (pop pattern) - (pop qualifiers)) - (t (return nil))))) + (return t)) + ((eq pattern '*) (return t)) + ((and pattern qualifiers (eq (car pattern) (car qualifiers))) + (pop pattern) + (pop qualifiers)) + (t (return nil))))) (defun make-default-method-group-description (patterns) (if (cdr patterns) (format nil - "methods matching one of the patterns: ~{~S, ~} ~S" - (butlast patterns) (car (last patterns))) + "methods matching one of the patterns: ~{~S, ~} ~S" + (butlast patterns) (car (last patterns))) (format nil - "methods matching the pattern: ~S" - (car patterns)))) + "methods matching the pattern: ~S" + (car patterns)))) ;;; This baby is a complete mess. I can't believe we put it in this ;;; way. No doubt this is a large part of what drives MLY crazy. @@ -440,53 +437,53 @@ ;;; hybrid of PARSE-LAMBDA-LIST and PARSE-DEFMACRO-LAMBDA-LIST. (defun deal-with-args-option (wrapped-body args-lambda-list) (let ((intercept-rebindings - (let (rebindings) - (dolist (arg args-lambda-list (nreverse rebindings)) - (unless (member arg lambda-list-keywords) - (typecase arg - (symbol (push `(,arg ',arg) rebindings)) - (cons - (unless (symbolp (car arg)) - (error "invalid lambda-list specifier: ~S." arg)) - (push `(,(car arg) ',(car arg)) rebindings)) - (t (error "invalid lambda-list-specifier: ~S." arg))))))) - (nreq 0) - (nopt 0) - (whole nil)) + (let (rebindings) + (dolist (arg args-lambda-list (nreverse rebindings)) + (unless (member arg lambda-list-keywords) + (typecase arg + (symbol (push `(,arg ',arg) rebindings)) + (cons + (unless (symbolp (car arg)) + (error "invalid lambda-list specifier: ~S." arg)) + (push `(,(car arg) ',(car arg)) rebindings)) + (t (error "invalid lambda-list-specifier: ~S." arg))))))) + (nreq 0) + (nopt 0) + (whole nil)) ;; Count the number of required and optional parameters in ;; ARGS-LAMBDA-LIST into NREQ and NOPT, and set WHOLE to the ;; name of a &WHOLE parameter, if any. (when (member '&whole (rest args-lambda-list)) (error 'simple-program-error - :format-control "~@" - :format-arguments (list args-lambda-list))) + :format-arguments (list args-lambda-list))) (loop with state = 'required - for arg in args-lambda-list do - (if (memq arg lambda-list-keywords) - (setq state arg) - (case state - (required (incf nreq)) - (&optional (incf nopt)) - (&whole (setq whole arg state 'required))))) + for arg in args-lambda-list do + (if (memq arg lambda-list-keywords) + (setq state arg) + (case state + (required (incf nreq)) + (&optional (incf nopt)) + (&whole (setq whole arg state 'required))))) ;; This assumes that the head of WRAPPED-BODY is a let, and it ;; injects let-bindings of the form (ARG 'SYM) for all variables ;; of the argument-lambda-list; SYM is a gensym. (aver (memq (first wrapped-body) '(let let*))) (setf (second wrapped-body) - (append intercept-rebindings (second wrapped-body))) + (append intercept-rebindings (second wrapped-body))) ;; Be sure to fill out the args lambda list so that it can be too ;; short if it wants to. (unless (or (memq '&rest args-lambda-list) - (memq '&allow-other-keys args-lambda-list)) + (memq '&allow-other-keys args-lambda-list)) (let ((aux (memq '&aux args-lambda-list))) - (setq args-lambda-list - (append (ldiff args-lambda-list aux) - (if (memq '&key args-lambda-list) - '(&allow-other-keys) - '(&rest .ignore.)) - aux)))) + (setq args-lambda-list + (append (ldiff args-lambda-list aux) + (if (memq '&key args-lambda-list) + '(&allow-other-keys) + '(&rest .ignore.)) + aux)))) ;; .GENERIC-FUNCTION. is bound to the generic function in the ;; method combination function, and .GF-ARGS* is bound to the ;; generic function arguments in effective method functions @@ -505,19 +502,19 @@ ;; produces the value of actual argument that is bound to the ;; symbol. `(let ((inner-result. ,wrapped-body) - (gf-lambda-list (generic-function-lambda-list .generic-function.))) + (gf-lambda-list (generic-function-lambda-list .generic-function.))) `(destructuring-bind ,',args-lambda-list - (frob-combined-method-args - .gf-args. ',gf-lambda-list - ,',nreq ,',nopt) - ,,(when (memq '.ignore. args-lambda-list) - ''(declare (ignore .ignore.))) - ;; If there is a &WHOLE in the args-lambda-list, let - ;; it result in the actual arguments of the generic-function - ;; not the frobbed list. - ,,(when whole - ``(setq ,',whole .gf-args.)) - ,inner-result.)))) + (frob-combined-method-args + .gf-args. ',gf-lambda-list + ,',nreq ,',nopt) + ,,(when (memq '.ignore. args-lambda-list) + ''(declare (ignore .ignore.))) + ;; If there is a &WHOLE in the args-lambda-list, let + ;; it result in the actual arguments of the generic-function + ;; not the frobbed list. + ,,(when whole + ``(setq ,',whole .gf-args.)) + ,inner-result.)))) ;;; Partition VALUES into three sections: required, optional, and the ;;; rest, according to required, optional, and other parameters in @@ -527,23 +524,23 @@ ;;; is left as rest from VALUES. (defun frob-combined-method-args (values lambda-list nreq nopt) (loop with section = 'required - for arg in lambda-list - if (memq arg lambda-list-keywords) do - (setq section arg) - (unless (eq section '&optional) - (loop-finish)) - else if (eq section 'required) - count t into nr - and collect (pop values) into required - else if (eq section '&optional) - count t into no - and collect (pop values) into optional - finally - (flet ((frob (list n m) - (cond ((> n m) (butlast list (- n m))) - ((< n m) (nconc list (make-list (- m n)))) - (t list)))) - (return (nconc (frob required nr nreq) - (frob optional no nopt) - values))))) + for arg in lambda-list + if (memq arg lambda-list-keywords) do + (setq section arg) + (unless (eq section '&optional) + (loop-finish)) + else if (eq section 'required) + count t into nr + and collect (pop values) into required + else if (eq section '&optional) + count t into no + and collect (pop values) into optional + finally + (flet ((frob (list n m) + (cond ((> n m) (butlast list (- n m))) + ((< n m) (nconc list (make-list (- m n)))) + (t list)))) + (return (nconc (frob required nr nreq) + (frob optional no nopt) + values)))))