common-lisp - 测试符号是否是 Common Lisp 中的 defstruct 名称

Question

有没有比这更简单的方法来测试符号是否是结构的名称：

(fboundp 'make-symbol)

Answer 1

(defun symbol-names-structure-p (symbol)
  (let ((class (find-class symbol nil)))
    (and class (typep class 'structure-class))))

CL-USER 11 > (defstruct foo bar)
FOO

CL-USER 12 > (symbol-names-structure-p 'bar)
NIL

CL-USER 13 > (symbol-names-structure-p 'foo)
T

还：

CL-USER 14 > (ignore-errors (subtypep 'foo 'structure-object))
T
T

CL-USER 15 > (ignore-errors (subtypep 'bar 'structure-object))
NIL
#<CONDITIONS:ILLEGAL-TYPE-SPECIFIER 402001578B>