FIGURE 1: Liana Example of Encapsulation.

// EDITWIND.L - Text editor window.

class editwindow: window {
  window ed;
  void editwindow ()
    {
      window ();
      this.home;
      this << (ed = new edittext);
      ed.multiline = true;
      ed.hscroll = true;
      ed.vscroll = true;
      ed.autohscroll = true;
      ed.autovscroll = true;
      resize_control ();
      ed.show;
      got_focus ();
    }
  void editwindow (string title)
    {
      editwindow ();
      this.text = title;
    }
  void got_focus () {if (ed) ed.have_focus = true;}
  void resized (int width, int height) {resize_control ();}   void
resize_control ()
    {
      update_status_line_position ();
      if (ed) {
        ed.width = this.width + 1;
        ed.height = this.height + 1;
        ed.x = -1;
        ed.y = -1;
    }
  }
  bool status_line_enabled_set (bool status_line_enabled)
  {
    window::status_line_enabled_set (status_line_enabled);
    resize_control ();
  }
};

// FILEWIND.L - Window that displays contents of a text file.

class filewindow: textwindow {
  public:
    string path;
  void filewindow (string path)
  {
    // Initialize the text window.
    textwindow (title (path));
    // Try to open the file.
    if (! (file f = fopen (path))) {
      error ("Unable to open file: "+path);
      exit (3);
      }
    // Read the contents of the file.
    while (string line = f.readline)
      this << line;
    fclose (f);
    // Display the text read from the file.
    this.first_row = 0;
    show ();
    // Remember the path.
    filewindow::path = path;
  }
};