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 Identifier for the entity class that the service applies to |
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222 | * Typically a Fully Qualified Class Name |
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223 | * @param mixed $service |
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224 | * @return bool |
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225 | */ |
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226 | public function addService($identifier, $service) |
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232 | |||
233 | |||
234 | |||
235 | /** |
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236 | * Adds instructions on how to brew objects |
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237 | * |
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238 | * @param RecipeInterface $recipe |
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239 | * @return mixed |
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240 | */ |
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241 | public function addRecipe(RecipeInterface $recipe) |
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247 | |||
248 | |||
249 | |||
250 | /** |
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251 | * Get instructions on how to brew objects |
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252 | * |
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253 | * @param string $identifier Identifier for the entity class that the recipe applies to |
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254 | * Typically a Fully Qualified Class Name |
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255 | * @param string $type |
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256 | * @return RecipeInterface |
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257 | */ |
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258 | public function getRecipe($identifier, $type = '') |
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287 | |||
288 | |||
289 | |||
290 | /** |
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291 | * adds class name aliases to list of filters |
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292 | * |
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293 | * @param string $identifier Identifier for the entity class that the alias applies to |
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294 | * Typically a Fully Qualified Class Name |
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295 | * @param array $aliases |
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296 | * @return void |
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297 | * @throws InvalidIdentifierException |
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298 | */ |
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299 | public function addAliases($identifier, $aliases) |
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309 | |||
310 | |||
311 | |||
312 | /** |
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313 | * Adds a service to one of the internal collections |
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314 | * |
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315 | * @param $identifier |
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316 | * @param array $arguments |
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317 | * @param string $type |
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318 | * @return mixed |
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319 | * @throws ServiceExistsException |
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320 | */ |
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321 | private function makeCoffee($identifier, $arguments = array(), $type = '') |
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332 | |||
333 | |||
334 | |||
335 | /** |
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336 | * filters alias identifiers to find the real class name |
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337 | * |
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338 | * @param string $identifier Identifier for the entity class that the filter applies to |
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339 | * Typically a Fully Qualified Class Name |
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340 | * @return string |
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341 | * @throws InvalidIdentifierException |
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342 | */ |
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343 | private function filterIdentifier($identifier) |
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350 | |||
351 | |||
352 | |||
353 | /** |
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354 | * verifies and standardizes identifiers |
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355 | * |
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356 | * @param string $identifier Identifier for the entity class |
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357 | * Typically a Fully Qualified Class Name |
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358 | * @return string |
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359 | * @throws InvalidIdentifierException |
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360 | */ |
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361 | View Code Duplication | private function processIdentifier($identifier) |
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371 | |||
372 | |||
373 | |||
374 | /** |
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375 | * @param string $type |
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376 | * @return CoffeeMakerInterface |
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377 | * @throws InvalidDataTypeException |
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378 | * @throws InvalidClassException |
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379 | */ |
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380 | private function getCoffeeMaker($type) |
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389 | |||
390 | |||
391 | |||
392 | /** |
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393 | * Retrieves all recipes that use a wildcard "*" in their identifier |
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394 | * This allows recipes to be set up for handling |
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395 | * legacy classes that do not support PSR-4 autoloading. |
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396 | * for example: |
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397 | * using "EEM_*" for a recipe identifier would target all legacy models like EEM_Attendee |
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398 | * |
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399 | * @return array |
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400 | */ |
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401 | private function getDefaultRecipes() |
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416 | |||
417 | |||
418 | |||
419 | /** |
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420 | * clones a default recipe and then copies details |
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421 | * from the incoming request to it so that it can be used |
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422 | * |
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423 | * @param RecipeInterface $default_recipe |
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424 | * @param string $identifier |
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425 | * @param string $type |
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426 | * @return RecipeInterface |
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427 | */ |
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428 | private function copyDefaultRecipe(RecipeInterface $default_recipe, $identifier, $type = '') |
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450 | |||
451 | |||
452 | |||
453 | /** |
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454 | * @param string $identifier Identifier for the entity class that the service applies to |
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455 | * Typically a Fully Qualified Class Name |
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456 | * @param mixed $service |
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457 | * @return object |
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458 | * @throws InvalidServiceException |
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459 | */ |
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460 | private function validateService($identifier, $service) |
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470 | |||
471 | } |
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472 | // End of file CoffeeShop.php |
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473 | // 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..