WordPress Custom Page Widget

`class Custom_Pages_Widgets extends WP_Widget{
  public function __construct(){
      $widget_ops = array(
                      'description' => __( "A list of your site’s Pages." )
                    );
    parent::__construct( 'custom_widget_pages', __( 'Widget Pages' ), $widget_ops );
  }
  public function widget( $args, $instance ){
    extract($args);
    $select = empty( $instance['select'] ) ? '' : $instance['select'];
    echo $args['before_widget'];
    echo $args['before_title'];
    ?>
    <div class="widget-list">
      <ul>
        <?php
          foreach ($select as $post_id) {
            echo '<li><a href="'.get_the_permalink($post_id).'">'.esc_attr(get_the_title($post_id)).'</a></li>';
          }
        ?>
      </ul>
    </div>
    <?php
    echo $args['after_title'];
    echo $args['after_widget'];

  }
  public function update( $new_instance, $old_instance ){
      $instance = $old_instance;
      $instance['select'] = esc_sql( $new_instance['select'] );
      return $instance;
  }

  public function form( $instance ){
      if( $instance )
        $select = $instance['select'];
      else
        $select ='';

      $get_page = get_pages( array(
          'order' => 'DESC',
          'posts_per_page' => 200,
          'post_status' => 'publish',
          'post_type' => 'page',
      ));
      if( $get_page ){
          printf(
              '<select
                  multiple="multiple"
                  name="%s[]"
                  id="%s"
                  class="widefat"
                  size="10"
                  style="margin: 5px;">',
              $this->get_field_name('select'),
              $this->get_field_id('select')
          );
          foreach( $get_page as $page )
          {
              printf(
                  '<option value="%s" class="widefat" %s>%s</option>',
                  $page->ID,
                  in_array( $page->ID, $select) ? 'selected="selected"' : '',
                  $page->post_title
              );
          }
          echo '</select>';
      }
      else
          echo 'No Pages have found :(';
  }
}
add_action('widgets_init', 'custom_widget_pages');
function custom_widget_pages(){
    register_widget('Custom_Pages_Widgets');
}`