D语言私有成员

import std.stdio;

class Box { 
   public: 
      double length; 

      // Member functions definitions
      double getWidth() { 
         return width ; 
      } 
      void setWidth( double wid ) { 
         width = wid; 
      }

   private: 
      double width; 
}

// Main function for the program 
void main( ) { 
   Box box = new Box();

   box.length = 10.0; 
   writeln("Length of box : ", box.length);

   box.setWidth(10.0);  
   writeln("Width of box : ", box.getWidth()); 
}