Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like CoffeeShop 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 CoffeeShop, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 31 | class CoffeeShop implements CoffeePotInterface |
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| 32 | { |
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| 33 | |||
| 34 | |||
| 35 | /** |
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| 36 | * This was the best coffee related name I could think of to represent class name "aliases" |
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| 37 | * So classes can be found via an alias identifier, |
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| 38 | * that is revealed when it is run through... the filters... eh? get it? |
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| 39 | * |
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| 40 | * @var array $filters |
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| 41 | */ |
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| 42 | private $filters = array(); |
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| 43 | |||
| 44 | /** |
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| 45 | * These are the classes that will actually build the objects (to order of course) |
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| 46 | * |
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| 47 | * @var array $coffee_makers |
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| 48 | */ |
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| 49 | private $coffee_makers = array(); |
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| 50 | |||
| 51 | /** |
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| 52 | * where the instantiated "singleton" objects are stored |
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| 53 | * |
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| 54 | * @var CollectionInterface $carafe |
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| 55 | */ |
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| 56 | private $carafe; |
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| 57 | |||
| 58 | /** |
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| 59 | * collection of Recipes that instruct us how to brew objects |
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| 60 | * |
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| 61 | * @var CollectionInterface $recipes |
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| 62 | */ |
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| 63 | private $recipes; |
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| 64 | |||
| 65 | /** |
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| 66 | * collection of closures for brewing objects |
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| 67 | * |
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| 68 | * @var CollectionInterface $reservoir |
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| 69 | */ |
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| 70 | private $reservoir; |
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| 71 | |||
| 72 | |||
| 73 | |||
| 74 | /** |
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| 75 | * CoffeeShop constructor |
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| 76 | */ |
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| 77 | public function __construct() |
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| 90 | |||
| 91 | |||
| 92 | |||
| 93 | /** |
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| 94 | * Returns true if the container can return an entry for the given identifier. |
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| 95 | * Returns false otherwise. |
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| 96 | * `has($identifier)` returning true does not mean that `get($identifier)` will not throw an exception. |
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| 97 | * It does however mean that `get($identifier)` will not throw a `ServiceNotFoundException`. |
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| 98 | * |
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| 99 | * @param string $identifier Identifier of the entry to look for. |
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| 100 | * Typically a Fully Qualified Class Name |
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| 101 | * @return boolean |
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| 102 | */ |
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| 103 | public function has($identifier) |
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| 108 | |||
| 109 | |||
| 110 | |||
| 111 | /** |
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| 112 | * finds a previously brewed (SHARED) service and returns it |
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| 113 | * |
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| 114 | * @param string $identifier Identifier for the entity class to be constructed. |
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| 115 | * Typically a Fully Qualified Class Name |
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| 116 | * @return mixed |
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| 117 | * @throws ServiceNotFoundException No service was found for this identifier. |
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| 118 | */ |
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| 119 | public function get($identifier) |
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| 127 | |||
| 128 | |||
| 129 | |||
| 130 | /** |
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| 131 | * returns an instance of the requested entity type using the supplied arguments. |
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| 132 | * If a shared service is requested and an instance is already in the carafe, then it will be returned. |
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| 133 | * If it is not already in the carafe, then the service will be constructed, added to the carafe, and returned |
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| 134 | * If the request is for a new entity and a closure exists in the reservoir for creating it, |
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| 135 | * then a new entity will be instantiated from the closure and returned. |
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| 136 | * If a closure does not exist, then one will be built and added to the reservoir |
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| 137 | * before instantiating the requested entity. |
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| 138 | * |
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| 139 | * @param string $identifier Identifier for the entity class to be constructed. |
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| 140 | * Typically a Fully Qualified Class Name |
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| 141 | * @param array $arguments an array of arguments to be passed to the entity constructor |
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| 142 | * @param string $type |
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| 143 | * @return mixed |
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| 144 | * @throws ServiceNotFoundException No service was found for this identifier. |
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| 145 | */ |
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| 146 | public function brew($identifier, $arguments = array(), $type = '') |
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| 185 | |||
| 186 | |||
| 187 | |||
| 188 | /** |
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| 189 | * @param CoffeeMakerInterface $coffee_maker |
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| 190 | * @param string $type |
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| 191 | * @return bool |
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| 192 | */ |
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| 193 | public function addCoffeeMaker(CoffeeMakerInterface $coffee_maker, $type) |
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| 198 | |||
| 199 | |||
| 200 | |||
| 201 | /** |
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| 202 | * @param string $identifier |
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| 203 | * @param callable $closure |
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| 204 | * @return callable|null |
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| 205 | */ |
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| 206 | public function addClosure($identifier, $closure) |
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| 217 | |||
| 218 | |||
| 219 | |||
| 220 | /** |
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| 221 | * @param string $identifier |
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| 222 | * @return boolean |
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| 223 | */ |
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| 224 | View Code Duplication | public function removeClosure($identifier) |
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| 225 | { |
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| 226 | $identifier = $this->processIdentifier($identifier); |
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| 227 | if ($this->reservoir->has($identifier)) { |
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| 228 | $this->reservoir->remove($this->reservoir->get($identifier)); |
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| 229 | if ( ! $this->reservoir->has($identifier)) { |
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| 230 | return true; |
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| 231 | } |
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| 232 | } |
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| 233 | return false; |
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| 234 | } |
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| 235 | |||
| 236 | |||
| 237 | |||
| 238 | /** |
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| 239 | * @param string $identifier Identifier for the entity class that the service applies to |
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| 240 | * Typically a Fully Qualified Class Name |
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| 241 | * @param mixed $service |
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| 242 | * @return bool |
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| 243 | */ |
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| 244 | public function addService($identifier, $service) |
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| 250 | |||
| 251 | |||
| 252 | |||
| 253 | /** |
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| 254 | * @param string $identifier |
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| 255 | * @return boolean |
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| 256 | */ |
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| 257 | View Code Duplication | public function removeService($identifier) |
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| 258 | { |
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| 259 | $identifier = $this->processIdentifier($identifier); |
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| 260 | if ($this->carafe->has($identifier)) { |
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| 261 | $this->carafe->remove($this->carafe->get($identifier)); |
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| 262 | if ( ! $this->carafe->has($identifier)) { |
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| 263 | return true; |
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| 264 | } |
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| 265 | } |
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| 266 | return false; |
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| 267 | } |
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| 268 | |||
| 269 | |||
| 270 | |||
| 271 | /** |
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| 272 | * Adds instructions on how to brew objects |
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| 273 | * |
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| 274 | * @param RecipeInterface $recipe |
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| 275 | * @return mixed |
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| 276 | */ |
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| 277 | public function addRecipe(RecipeInterface $recipe) |
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| 283 | |||
| 284 | |||
| 285 | |||
| 286 | /** |
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| 287 | * @param string $identifier The Recipe's identifier |
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| 288 | * @return boolean |
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| 289 | */ |
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| 290 | View Code Duplication | public function removeRecipe($identifier) |
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| 291 | { |
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| 292 | $identifier = $this->processIdentifier($identifier); |
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| 293 | if ($this->recipes->has($identifier)) { |
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| 294 | $this->recipes->remove( |
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| 295 | $this->recipes->get($identifier) |
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| 296 | ); |
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| 297 | if ( ! $this->recipes->has($identifier)) { |
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| 298 | return true; |
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| 299 | } |
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| 300 | } |
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| 301 | return false; |
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| 302 | } |
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| 303 | |||
| 304 | |||
| 305 | |||
| 306 | /** |
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| 307 | * Get instructions on how to brew objects |
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| 308 | * |
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| 309 | * @param string $identifier Identifier for the entity class that the recipe applies to |
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| 310 | * Typically a Fully Qualified Class Name |
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| 311 | * @param string $type |
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| 312 | * @return RecipeInterface |
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| 313 | */ |
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| 314 | public function getRecipe($identifier, $type = '') |
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| 315 | { |
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| 316 | $identifier = $this->processIdentifier($identifier); |
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| 317 | if ($this->recipes->has($identifier)) { |
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| 318 | return $this->recipes->get($identifier); |
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| 319 | } |
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| 320 | $default_recipes = $this->getDefaultRecipes(); |
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| 321 | $matches = array(); |
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| 322 | foreach ($default_recipes as $wildcard => $default_recipe) { |
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| 323 | // is the wildcard recipe prefix in the identifier ? |
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| 324 | if (strpos($identifier, $wildcard) !== false) { |
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| 325 | // track matches and use the number of wildcard characters matched for the key |
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| 326 | $matches[strlen($wildcard)] = $default_recipe; |
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| 327 | } |
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| 328 | } |
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| 329 | if (count($matches) > 0) { |
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| 330 | // sort our recipes by the number of wildcard characters matched |
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| 331 | ksort($matches); |
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| 332 | // then grab the last recipe form the list, since it had the most matching characters |
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| 333 | $match = array_pop($matches); |
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| 334 | // since we are using a default recipe, we need to set it's identifier and fqcn |
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| 335 | return $this->copyDefaultRecipe($match, $identifier, $type); |
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| 336 | } |
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| 337 | if ($this->recipes->has(Recipe::DEFAULT_ID)) { |
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| 338 | // since we are using a default recipe, we need to set it's identifier and fqcn |
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| 339 | return $this->copyDefaultRecipe($this->recipes->get(Recipe::DEFAULT_ID), $identifier, $type); |
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| 340 | } |
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| 341 | throw new OutOfBoundsException( |
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| 342 | sprintf( |
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| 343 | __('Could not brew coffee because no recipes were found for class "%1$s".', 'event_espresso'), |
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| 344 | $identifier |
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| 345 | ) |
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| 346 | ); |
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| 347 | } |
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| 348 | |||
| 349 | |||
| 350 | |||
| 351 | /** |
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| 352 | * adds class name aliases to list of filters |
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| 353 | * |
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| 354 | * @param string $identifier Identifier for the entity class that the alias applies to |
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| 355 | * Typically a Fully Qualified Class Name |
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| 356 | * @param array $aliases |
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| 357 | * @return void |
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| 358 | * @throws InvalidIdentifierException |
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| 359 | */ |
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| 360 | public function addAliases($identifier, $aliases) |
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| 370 | |||
| 371 | |||
| 372 | |||
| 373 | /** |
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| 374 | * Adds a service to one of the internal collections |
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| 375 | * |
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| 376 | * @param $identifier |
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| 377 | * @param array $arguments |
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| 378 | * @param string $type |
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| 379 | * @return mixed |
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| 380 | * @throws ServiceExistsException |
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| 381 | */ |
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| 382 | private function makeCoffee($identifier, $arguments = array(), $type = '') |
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| 393 | |||
| 394 | |||
| 395 | |||
| 396 | /** |
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| 397 | * filters alias identifiers to find the real class name |
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| 398 | * |
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| 399 | * @param string $identifier Identifier for the entity class that the filter applies to |
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| 400 | * Typically a Fully Qualified Class Name |
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| 401 | * @return string |
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| 402 | * @throws InvalidIdentifierException |
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| 403 | */ |
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| 404 | private function filterIdentifier($identifier) |
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| 411 | |||
| 412 | |||
| 413 | |||
| 414 | /** |
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| 415 | * verifies and standardizes identifiers |
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| 416 | * |
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| 417 | * @param string $identifier Identifier for the entity class |
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| 418 | * Typically a Fully Qualified Class Name |
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| 419 | * @return string |
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| 420 | * @throws InvalidIdentifierException |
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| 421 | */ |
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| 422 | View Code Duplication | private function processIdentifier($identifier) |
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| 432 | |||
| 433 | |||
| 434 | |||
| 435 | /** |
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| 436 | * @param string $type |
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| 437 | * @return CoffeeMakerInterface |
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| 438 | * @throws InvalidDataTypeException |
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| 439 | * @throws InvalidClassException |
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| 440 | */ |
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| 441 | private function getCoffeeMaker($type) |
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| 450 | |||
| 451 | |||
| 452 | |||
| 453 | /** |
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| 454 | * Retrieves all recipes that use a wildcard "*" in their identifier |
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| 455 | * This allows recipes to be set up for handling |
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| 456 | * legacy classes that do not support PSR-4 autoloading. |
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| 457 | * for example: |
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| 458 | * using "EEM_*" for a recipe identifier would target all legacy models like EEM_Attendee |
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| 459 | * |
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| 460 | * @return array |
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| 461 | */ |
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| 462 | private function getDefaultRecipes() |
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| 477 | |||
| 478 | |||
| 479 | |||
| 480 | /** |
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| 481 | * clones a default recipe and then copies details |
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| 482 | * from the incoming request to it so that it can be used |
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| 483 | * |
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| 484 | * @param RecipeInterface $default_recipe |
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| 485 | * @param string $identifier |
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| 486 | * @param string $type |
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| 487 | * @return RecipeInterface |
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| 488 | */ |
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| 489 | private function copyDefaultRecipe(RecipeInterface $default_recipe, $identifier, $type = '') |
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| 511 | |||
| 512 | |||
| 513 | |||
| 514 | /** |
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| 515 | * @param string $identifier Identifier for the entity class that the service applies to |
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| 516 | * Typically a Fully Qualified Class Name |
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| 517 | * @param mixed $service |
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| 518 | * @return object |
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| 519 | * @throws InvalidServiceException |
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| 520 | */ |
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| 521 | private function validateService($identifier, $service) |
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| 531 | |||
| 532 | } |
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| 533 | // End of file CoffeeShop.php |
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| 534 | // Location: /CoffeeShop.php |
Our type inference engine has found an assignment to a property that is incompatible with the declared type of that property.
Either this assignment is in error or the assigned type should be added to the documentation/type hint for that property..