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 |
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| 23 | class ShoppingCart extends \yz\shoppingcart\ShoppingCart |
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| 24 | { |
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| 25 | /** |
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| 26 | * @var CartPositionInterface[] |
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| 27 | * TODO make local AbstractCartPosition |
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| 28 | */ |
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| 29 | protected $_positions = []; |
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| 30 | |||
| 31 | /** |
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| 32 | * The cart module. |
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| 33 | */ |
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| 34 | public $module; |
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| 35 | |||
| 36 | public function behaviors() |
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| 44 | 1 | ||
| 45 | /** |
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| 46 | 1 | * @return integer |
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| 47 | 1 | */ |
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| 48 | 1 | public function getCount(): int |
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| 59 | 2 | ||
| 60 | public function findRelatedFor(CartPositionInterface $parent): ?CartPositionInterface |
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| 70 | |||
| 71 | 1 | /** |
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| 72 | * @return CartPositionInterface[] |
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| 73 | */ |
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| 74 | public function getRootPositions(): array |
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| 80 | |||
| 81 | public function getQuantity() |
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| 90 | |||
| 91 | public function getSubtotal() |
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| 95 | |||
| 96 | public function getTotal() |
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| 100 | |||
| 101 | public function getDiscount() |
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| 105 | |||
| 106 | public function formatCurrency($sum, $currency = null) |
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| 110 | |||
| 111 | /** |
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| 112 | * Sets cart from serialized string |
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| 113 | * @param string $serialized |
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| 114 | */ |
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| 115 | public function setSerialized($serialized) |
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| 125 | |||
| 126 | /** |
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| 127 | * Checks whether any of cart positions has error in `id` attribute. |
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| 128 | * @return boolean |
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| 129 | */ |
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| 130 | public function hasErrors() |
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| 140 | |||
| 141 | /** |
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| 142 | * @param CartPositionInterface[] $positions |
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| 143 | */ |
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| 144 | public function putPositions($positions) |
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| 171 | |||
| 172 | |||
| 173 | /** |
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| 174 | * This cart does not support multi-currency checkout. |
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| 175 | * |
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| 176 | * @return string|null When the cart is empty, returns {@see getDefaultCurrency()}. |
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| 177 | * When cart has at least one position, returns the first position currency. |
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| 178 | * Note, that the position currency may be undefined – in this case, `null` will be returned. |
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| 179 | */ |
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| 180 | public function getCurrency(): ?string |
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| 188 | |||
| 189 | /** |
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| 190 | * Returns a default cart currency |
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| 191 | * |
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| 192 | * @return string |
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| 193 | */ |
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| 194 | public function getDefaultCurrency(): string |
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| 198 | |||
| 199 | /** |
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| 200 | * @return array |
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| 201 | */ |
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| 202 | public function getAdditionalLinks(): array |
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| 224 | |||
| 225 | /** |
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| 226 | * @var CartActionEvent[]|null |
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| 227 | */ |
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| 228 | private $_accumulatedEvents; |
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| 229 | public function trigger($name, Event $event = null) |
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| 238 | |||
| 239 | /** |
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| 240 | * Runs $closure and accumulates all events occurred during $closure run. |
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| 241 | * Events get released immediately after a success $closure run. |
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| 242 | * |
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| 243 | * The method can be used to prevent useless calculations that happen after |
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| 244 | * bunch of similar updates on a cart. |
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| 245 | * |
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| 246 | * @param \Closure $closure |
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| 247 | */ |
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| 248 | public function accumulateEvents(\Closure $closure): void |
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| 263 | } |
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| 264 |
If you access a property on an interface, you most likely code against a concrete implementation of the interface.
Available Fixes
Adding an additional type check:
Changing the type hint: