Esempio plugin per WooCommerce che aggiunge una colonna

woo-iva.php

<?php
/**
 * Plugin Name: WooCommerce Colonna IVA
 * Description: Aggiunge una colonna nei prodotti WooCommerce
 * Version: 1.0.0
 * Author: LUGRieti
 * Author URI:
 * Requires at least: 4.9
 * Tested up to: 4.9
 *
 */

// https://github.com/WPBP/CPT_Columns
include('CPT_Columns.php');

add_action( 'plugins_loaded', 'aggiungi_colonna', 0 );

function aggiungi_colonna() {
    $post_columns = new CPT_columns( 'product' );
    $post_columns->add_column( 'iva', array(
        'label' => __( 'IVA' ),
        'type' => 'custom_value',
        'sortable' => true,
        'callback' => 'calcola_iva',
        'def' => 'Not defined', // Default value in case post meta not found
        'order' => '-1' // This is the last column
        )
    );
}

function calcola_iva() {
    $product = wc_get_product( get_the_ID() );
    $print = '€ ' . $product->get_price() * ( 22/100 );

    return $print;
}