Woocommerce cart price customization

<?php
  add_action( 'woocommerce_before_calculate_totals', 'add_custom_price', 10, 1);

  function add_custom_price( $cart_obj ) {	
     // This is necessary for WC 3.0+
      if ( is_admin() && ! defined( 'DOING_AJAX' ) )
          return;

      // Avoiding hook repetition (when using price calculations for example)
      if ( did_action( 'woocommerce_before_calculate_totals' ) >= 2 )
          return;

    foreach ( $cart_obj->get_cart() as $key => $value ) {
      $weight = $value['data']->weight;
      $price = $value['data']->price;
      $newprice = $price * (float)$weight;
        $value['data']->set_price($newprice);
      }
  }

  // Display the selected lenght value below cart item name
  add_filter( 'woocommerce_cart_item_name', 'display_select_length_after_cart_item_name', 10, 3 );
  function display_select_length_after_cart_item_name( $name, $cart_item, $cart_item_key ) {
      if( is_cart() && isset($cart_item['data']->weight) ) {
          $name .= '<p>'.__("Weight:") . ' ' . esc_html(wc_format_weight($cart_item['data']->weight)) . '</p> <br />';
          $name .= '<p><b>NB:</b> <i>This will influence the product price</i></p>';
      }
      return $name;
  }
?>