同一单元类之间的相互引用问题

Question

我在同一单元中定义了两个类,
type Trunk=Class
      protected
          PBXOwner:PBX;            // 中继所在的交换机
      public
      end;
type
     PBX=Class      //*1
      private
      protected
      public
     End;
在*1这里报错,说是标识符被重定义了,请问我在同一单元中该如何定义这两个类

Answer 1

type 
      PBX=Class;
      Trunk=Class
      protected
          PBXOwner:PBX;            // 中继所在的交换机
      public
      end;     PBX=Class      //*1
      private
      protected
      public
     End;