Complex classes like ShoppingCart 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 ShoppingCart, and based on these observations, apply Extract Interface, too.
| 1 | <?php | ||
| 24 | class ShoppingCart extends \yz\shoppingcart\ShoppingCart | ||
| 25 | { | ||
| 26 | /** | ||
| 27 | * @var AbstractCartPosition[] | ||
| 28 | * TODO make local AbstractCartPosition | ||
| 29 | */ | ||
| 30 | protected $_positions = []; | ||
| 31 | |||
| 32 | /** | ||
| 33 | * The cart module. | ||
| 34 | */ | ||
| 35 | public $module; | ||
| 36 | |||
| 37 | public function behaviors() | ||
| 45 | |||
| 46 | 1 | /** | |
| 47 | 1 | * @return integer | |
| 48 | 1 | */ | |
| 49 | public function getCount(): int | ||
| 60 | |||
| 61 | 2 | public function findRelatedFor(CartPositionInterface $parent): ?CartPositionInterface | |
| 71 | 1 | ||
| 72 | /** | ||
| 73 | * @return CartPositionInterface[] | ||
| 74 | */ | ||
| 75 | public function getRootPositions(): array | ||
| 81 | |||
| 82 | public function getQuantity() | ||
| 91 | |||
| 92 | public function getSubtotal() | ||
| 96 | |||
| 97 | public function getTotal() | ||
| 101 | |||
| 102 | public function getDiscount() | ||
| 106 | |||
| 107 | public function formatCurrency($sum, $currency = null) | ||
| 111 | |||
| 112 | /** | ||
| 113 | * Sets cart from serialized string | ||
| 114 | * @param string $serialized | ||
| 115 | */ | ||
| 116 | public function setSerialized($serialized) | ||
| 126 | |||
| 127 | /** | ||
| 128 | * Checks whether any of cart positions has error in `id` attribute. | ||
| 129 | * @return boolean | ||
| 130 | */ | ||
| 131 | public function hasErrors() | ||
| 141 | |||
| 142 | /** | ||
| 143 | * @param CartPositionInterface[] $positions | ||
| 144 | */ | ||
| 145 | public function putPositions($positions) | ||
| 168 | |||
| 169 | public function getCurrency(): ?string | ||
| 177 | |||
| 178 | /** | ||
| 179 | * @return array | ||
| 180 | */ | ||
| 181 | public function getAdditionalLinks(): array | ||
| 203 | |||
| 204 | /** | ||
| 205 | * @var CartActionEvent[]|null | ||
| 206 | */ | ||
| 207 | private $_accumulatedEvents; | ||
| 208 | public function trigger($name, Event $event = null) | ||
| 217 | |||
| 218 | /** | ||
| 219 | * Runs $closure and accumulates all events occurred during $closure run. | ||
| 220 | * Events get released immediately after a success $closure run. | ||
| 221 | * | ||
| 222 | * The method can be used to prevent useless calculations that happen after | ||
| 223 | * bunch of similar updates on a cart. | ||
| 224 | * | ||
| 225 | * @param \Closure $closure | ||
| 226 | */ | ||
| 227 | public function accumulateEvents(\Closure $closure): void | ||
| 242 | } | ||
| 243 | 
This check marks access to variables or properties that have not been declared yet. While PHP has no explicit notion of declaring a variable, accessing it before a value is assigned to it is most likely a bug.