reinitializing parent class WC_Product

// my plugin mimics the setup_product_data function

 function setup_product_data( $post ) {
    if ( is_int( $post ) ) $post = get_post( $post );
    if ( $post->post_type !== 'product' ) return;
    unset( $GLOBALS['product'] );
    $GLOBALS['product'] = new WC_Product_Suggested_Donation( $post->ID );
    return $GLOBALS['product'];
  }

//versus creating a new global object

  function setup_product_data( $post ) {
    if ( is_int( $post ) ) $post = get_post( $post );
    if ( $post->post_type !== 'product' ) return;
    unset( $GLOBALS['donation_product'] );
    $GLOBALS['donation_product'] = new WC_Product_Suggested_Donation( $post->ID );
    return $GLOBALS['donation_product'];
  }


//where

class WC_Product_Suggested_Donation extends WC_Product {

    static $suggested_donation = false;
    static $suggested_donation_singular = false;
    static $open_range = false;
    static $close_range = false;

    function __construct( $id ) {

        //reinitialize parent
        //is it efficient to do this? needed if i unset $GLOBALS['product'],
        //but not if i create my own global
        parent::__construct($id);
         }
}