使lisp中可打印的关闭对象
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28-09-2019 - |
题
如果您想以通用LISP打印的关闭对象(易于打印),则如何在不使用印刷和读取的情况下执行此操作。
解决方案
这样做有两个部分,至少在我的解决方案中,但是您需要此功能(感谢CL-Pravalence的家伙为此(警告)
(defun get-slots (object)
;; thanks to cl-prevalence
#+openmcl
(mapcar #'ccl:slot-definition-name
(#-openmcl-native-threads ccl:class-instance-slots
#+openmcl-native-threads ccl:class-slots
(class-of object)))
#+cmu
(mapcar #'pcl:slot-definition-name (pcl:class-slots (class-of object)))
#+sbcl
(mapcar #'sb-pcl:slot-definition-name (sb-pcl:class-slots (class-of object)))
#+lispworks
(mapcar #'hcl:slot-definition-name (hcl:class-slots (class-of object)))
#+allegro
(mapcar #'mop:slot-definition-name (mop:class-slots (class-of object)))
#+sbcl
(mapcar #'sb-mop:slot-definition-name (sb-mop:class-slots (class-of object)))
#+clisp
(mapcar #'clos:slot-definition-name (clos:class-slots (class-of object)))
#-(or openmcl cmu lispworks allegro sbcl clisp)
(error "not yet implemented"))
然后,要阅读,您将需要运行此代码,该代码设置了语法的1/2 { type-of-object ((slot-name . slot-value) (slot-name . slot-value) ...)
(set-macro-character
#\{
#'(lambda (str char)
(declare (ignore char))
(let ((list (read-delimited-list #\} str t)))
(let ((type (first list))
(list (second list)))
(let ((class (allocate-instance (find-class type))))
(loop for i in list do
(setf (slot-value class (car i)) (cdr i)))
class)))))
用于打印,使用
(defmethod print-object ((object standard-object) stream)
(format stream "{ ~s ~s}" (type-of object)
(loop for i in (get-slots object)
collect (cons i (slot-value object i)))))
一个 *print-readably*
强烈建议使用所有这些方法。另外,请注意,循环关系未经测试
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