＆＃34;全视图声明的说明必须出现在私人部分＆＃34;

Question

我收到一个错误，我找不到任何文档来解释我的代码中需要修复的内容。代码是：

   type BinarySearchTreePoint is limited private;
   type Node;
   type BinarySearchTreePoint is access Node;

   type Node is
      record
         Llink, Rlink : BinarySearchTreePoint;
         Ltag, Rtag : Boolean; --True indicates pointer to lower level,
                               -- False a thread.
         Info : Customer;
      end record;

我得到的错误是declaration of full view must appear in private part。它将此错误指向行type BinarySearchTreePoint is access Node;，并且我不确定错误消息的含义。

Answer 1

当您说type Foo is private;（或limited private）时，您需要在私人部分提供完整的声明;当然，这意味着你必须拥有私人部分。

您显示的代码将使用

进行编译

package Foo is
   type BinarySearchTreePoint is limited private;
private
   type Node;
   type BinarySearchTreePoint is access Node;

   type Node is
      record
         Llink, Rlink : BinarySearchTreePoint;
         ...

但是如果你需要在包裹外面看到Node，你需要说出像

这样的内容

package Foo is
   type BinarySearchTreePoint is limited private;
   type Node is private;
   --  stuff to do with getting a Node from a BinarySearchTreePoint??
   function Content (Of_Node : Node) return Customer;
private
   type BinarySearchTreePoint is access Node;

   type Node is
      record
         Llink, Rlink : BinarySearchTreePoint;
         ...