WordPress Widget with field title

widget-title.php

<?php
/*
Widget Name:
Description:
Author: davidperez
Author URI: https://www.closemarketing.es
*/
function widget_name() {
	register_widget( 'widget_name' );
}
add_action( 'widgets_init', 'widget_name' );

class widget_name extends WP_Widget {

	// CONSTRUCT WIDGET
	function widget_name() {
		$widget_ops = array(
			'classname' 	=> 'widget_name',
			'description' => '',
			'panels_icon' => 'dashicons dashicons-layout',
		);
		parent::__construct( 'widget_name', __( '', 'cmk' ), $widget_ops );
	}

	// CREATE WIDGET FORM (WORDPRESS DASHBOARD)
  function form($instance) {

	  if ( isset( $instance[ 'widget_title' ] ) ) {
      		$widget_title = $instance[ 'widget_title' ];
		}
		?>

        <p>
			<label for="<?php echo $this->get_field_id( 'widget_title' ); ?>"><?php _e( 'Título del Widget', 'tt' ); ?></label>
			<input name="<?php echo $this->get_field_name( 'widget_title' ); ?>" type="text" value="<?php echo esc_attr( $widget_title );?>" class="widefat"/>
		</p>

		<?php
  }

  // UPDATE WIDGET
  function update( $new_instance, $old_instance ) {

	$instance = $old_instance;
    $instance['widget_title'] = ( ! empty( $new_instance['widget_title'] ) ) ? strip_tags( $new_instance['widget_title'] ) : '';

	return $instance;

  }

  // DISPLAY WIDGET ON FRONT END
  function widget( $args, $instance ) {

	  extract( $args );

		// Widget starts to print information
        $before_widget = str_replace('" id=', ' widget_fullwidth" id=', $before_widget);
		echo $before_widget;
	
	if (isset($instance[ 'widget_title' ]))
		$widget_title = apply_filters( 'widget_title', $instance[ 'widget_title' ] ); else $widget_title = "";
        ?>


        <?php
		// Widget ends printing information
		echo $after_widget;
  }

}