定义二维数组的陷阱

Emacs-Lisp
2

如果 make-vector 第二个参数是 object 的话，就是指针赋值了：

DEFUN ("make-vector", Fmake_vector, Smake_vector, 2, 2, 0,
       doc: /* Return a newly created vector of length LENGTH, with each element being INIT.
See also the function `vector'.  */)
  (Lisp_Object length, Lisp_Object init)
{
  CHECK_NATNUM (length);
  struct Lisp_Vector *p = allocate_vector (XFASTINT (length));
  for (ptrdiff_t i = 0; i < XFASTINT (length); i++)
  p->contents[i] = init;
  return make_lisp_ptr (p, Lisp_Vectorlike);
 }

所以不管几维，修改的都是同一个 object。

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