Complex classes like WC_Shipping often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use WC_Shipping, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 17 | class WC_Shipping { |
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| 18 | |||
| 19 | /** @var bool True if shipping is enabled. */ |
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| 20 | public $enabled = false; |
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| 21 | |||
| 22 | /** @var array|null Stores methods loaded into woocommerce. */ |
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| 23 | public $shipping_methods = null; |
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| 24 | |||
| 25 | /** @var object|null Stores matching shipping zone. */ |
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| 26 | protected $shipping_zone = null; |
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| 27 | |||
| 28 | /** @var float Stores the cost of shipping */ |
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| 29 | public $shipping_total = 0; |
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| 30 | |||
| 31 | /** @var array Stores an array of shipping taxes. */ |
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| 32 | public $shipping_taxes = array(); |
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| 33 | |||
| 34 | /** @var array Stores the shipping classes. */ |
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| 35 | public $shipping_classes = array(); |
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| 36 | |||
| 37 | /** @var array Stores packages to ship and to get quotes for. */ |
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| 38 | public $packages = array(); |
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| 39 | |||
| 40 | /** |
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| 41 | * @var WC_Shipping The single instance of the class |
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| 42 | * @since 2.1 |
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| 43 | */ |
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| 44 | protected static $_instance = null; |
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| 45 | |||
| 46 | /** |
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| 47 | * Main WC_Shipping Instance. |
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| 48 | * |
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| 49 | * Ensures only one instance of WC_Shipping is loaded or can be loaded. |
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| 50 | * |
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| 51 | * @since 2.1 |
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| 52 | * @static |
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| 53 | * @return WC_Shipping Main instance |
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| 54 | */ |
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| 55 | public static function instance() { |
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| 61 | |||
| 62 | /** |
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| 63 | * Cloning is forbidden. |
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| 64 | * |
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| 65 | * @since 2.1 |
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| 66 | */ |
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| 67 | public function __clone() { |
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| 70 | |||
| 71 | /** |
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| 72 | * Unserializing instances of this class is forbidden. |
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| 73 | * |
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| 74 | * @since 2.1 |
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| 75 | */ |
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| 76 | public function __wakeup() { |
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| 79 | |||
| 80 | /** |
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| 81 | * Initialize shipping. |
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| 82 | */ |
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| 83 | public function __construct() { |
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| 90 | |||
| 91 | /** |
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| 92 | * Initialize shipping. |
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| 93 | */ |
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| 94 | public function init() { |
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| 97 | |||
| 98 | /** |
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| 99 | * Shipping methods register themselves by returning their main class name through the woocommerce_shipping_methods filter. |
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| 100 | * @return array |
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| 101 | */ |
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| 102 | public function get_shipping_method_class_names() { |
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| 122 | |||
| 123 | /** |
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| 124 | * Get matching shipping zone. |
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| 125 | * @return object|null |
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| 126 | */ |
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| 127 | public function get_shipping_zone() { |
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| 130 | |||
| 131 | /** |
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| 132 | * Loads all shipping methods which are hooked in. If a $package is passed some methods may add themselves conditionally. |
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| 133 | * |
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| 134 | * Loads all shipping methods which are hooked in. |
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| 135 | * If a $package is passed some methods may add themselves conditionally and zones will be used. |
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| 136 | * |
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| 137 | * @param array $package |
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| 138 | * @return array |
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| 139 | */ |
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| 140 | public function load_shipping_methods( $package = array() ) { |
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| 160 | |||
| 161 | /** |
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| 162 | * Register a shipping method. |
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| 163 | * |
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| 164 | * @param object|string $method Either the name of the method's class, or an instance of the method's class. |
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| 165 | */ |
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| 166 | public function register_shipping_method( $method ) { |
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| 178 | |||
| 179 | /** |
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| 180 | * Unregister shipping methods. |
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| 181 | */ |
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| 182 | public function unregister_shipping_methods() { |
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| 185 | |||
| 186 | /** |
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| 187 | * Returns all registered shipping methods for usage. |
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| 188 | * |
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| 189 | * @access public |
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| 190 | * @return array |
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| 191 | */ |
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| 192 | public function get_shipping_methods() { |
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| 198 | |||
| 199 | /** |
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| 200 | * Get an array of shipping classes. |
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| 201 | * |
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| 202 | * @access public |
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| 203 | * @return array |
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| 204 | */ |
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| 205 | public function get_shipping_classes() { |
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| 212 | |||
| 213 | /** |
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| 214 | * Calculate shipping for (multiple) packages of cart items. |
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| 215 | * |
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| 216 | * @param array $packages multi-dimensional array of cart items to calc shipping for. |
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| 217 | * @return array Array of calculated packages. |
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| 218 | */ |
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| 219 | public function calculate_shipping( $packages = array() ) { |
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| 246 | |||
| 247 | /** |
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| 248 | * See if package is shippable. |
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| 249 | * @param array $package |
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| 250 | * @return boolean |
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| 251 | */ |
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| 252 | protected function is_package_shippable( $package ) { |
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| 256 | |||
| 257 | /** |
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| 258 | * Calculate shipping rates for a package, |
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| 259 | * |
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| 260 | * Calculates each shipping methods cost. Rates are stored in the session based on the package hash to avoid re-calculation every page load. |
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| 261 | * |
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| 262 | * @param array $package cart items |
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| 263 | * @param int $package_key Index of the package being calculated. Used to cache multiple package rates. |
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| 264 | * @return array |
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| 265 | */ |
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| 266 | public function calculate_shipping_for_package( $package = array(), $package_key = 0 ) { |
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| 308 | |||
| 309 | /** |
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| 310 | * Get packages. |
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| 311 | * @return array |
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| 312 | */ |
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| 313 | public function get_packages() { |
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| 316 | |||
| 317 | /** |
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| 318 | * Reset shipping. |
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| 319 | * |
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| 320 | * Reset the totals for shipping as a whole. |
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| 321 | */ |
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| 322 | public function reset_shipping() { |
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| 328 | } |
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| 329 |
It seems like the type of the argument is not accepted by the function/method which you are calling.
In some cases, in particular if PHP’s automatic type-juggling kicks in this might be fine. In other cases, however this might be a bug.
We suggest to add an explicit type cast like in the following example: