Macros 定义Lisp宏时是否使用双引号(双逗号)?
当定义使用macrolet的宏或定义定义宏的宏时,似乎使用了Macros 定义Lisp宏时是否使用双引号(双逗号)?,macros,lisp,Macros,Lisp,当定义使用macrolet的宏或定义定义宏的宏时,似乎使用了,',或,来取消引用。有没有过我需要使用,的情况?当然 以下是来自: 另一个例子来自clx/gcontext.lisp: (macrolet ((def-gc-internals (name &rest extras) (let ((macros nil) (indexes nil) (masks nil)
,',
或,
来取消引用。有没有过我需要使用,
的情况?当然
以下是来自:
另一个例子来自clx/gcontext.lisp
:
(macrolet ((def-gc-internals (name &rest extras)
(let ((macros nil)
(indexes nil)
(masks nil)
(index 0))
(dolist (name *gcontext-components*)
(push `(defmacro ,(xintern 'gcontext-internal- name) (state)
`(svref ,state ,,index))
macros)
(setf (getf indexes name) index)
(push (ash 1 index) masks)
(incf index))
(dolist (extra extras)
(push `(defmacro ,(xintern 'gcontext-internal- (first extra)) (state)
`(svref ,state ,,index))
macros)
;; don't override already correct index entries
(unless (or (getf indexes (second extra)) (getf indexes (first extra)))
(setf (getf indexes (or (second extra) (first extra))) index))
(push (logior (ash 1 index)
(if (second extra)
(ash 1 (position (second extra) *gcontext-components*))
0))
masks)
(incf index))
`(within-definition (def-gc-internals ,name)
,@(nreverse macros)
(eval-when (:execute :compile-toplevel :load-toplevel)
(defparameter *gcontext-data-length* ,index)
(defparameter *gcontext-indexes* ',indexes)
(defparameter *gcontext-masks*
',(coerce (nreverse masks) 'simple-vector)))))))
(def-gc-internals ignore
(:clip :clip-mask) (:dash :dashes) (:font-obj :font) (:timestamp)))
简而言之,这并不常见,但也并非闻所未闻。@Robert the
=defun
示例似乎是为了将(=defun hello(xy)(+xy))
扩展到(progn(defmacro hello(xy)`(=hello*cont*,x,y))
,这是根据Lisp pdf上的继续部分。、index
示例似乎与、index
的作用相同,因为index
包含一个自评估的数字。此外,您可以决定(=defun hello(xy)(+xy))
应该扩展为(progn(defmacro hello(&rest args)`(=hello*cont*,@args))…)
相反,它消除了使用,@
,同时实现了相同的目标。
(macrolet ((def-gc-internals (name &rest extras)
(let ((macros nil)
(indexes nil)
(masks nil)
(index 0))
(dolist (name *gcontext-components*)
(push `(defmacro ,(xintern 'gcontext-internal- name) (state)
`(svref ,state ,,index))
macros)
(setf (getf indexes name) index)
(push (ash 1 index) masks)
(incf index))
(dolist (extra extras)
(push `(defmacro ,(xintern 'gcontext-internal- (first extra)) (state)
`(svref ,state ,,index))
macros)
;; don't override already correct index entries
(unless (or (getf indexes (second extra)) (getf indexes (first extra)))
(setf (getf indexes (or (second extra) (first extra))) index))
(push (logior (ash 1 index)
(if (second extra)
(ash 1 (position (second extra) *gcontext-components*))
0))
masks)
(incf index))
`(within-definition (def-gc-internals ,name)
,@(nreverse macros)
(eval-when (:execute :compile-toplevel :load-toplevel)
(defparameter *gcontext-data-length* ,index)
(defparameter *gcontext-indexes* ',indexes)
(defparameter *gcontext-masks*
',(coerce (nreverse masks) 'simple-vector)))))))
(def-gc-internals ignore
(:clip :clip-mask) (:dash :dashes) (:font-obj :font) (:timestamp)))