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 FrontMatterDocument 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 FrontMatterDocument, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 20 | abstract class FrontMatterDocument extends PermalinkDocument implements |
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| 21 | \ArrayAccess, |
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| 22 | JailedDocumentInterface, |
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| 23 | WritableDocumentInterface |
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| 24 | { |
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| 25 | const TEMPLATE = "---\n%s\n---\n\n%s"; |
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| 26 | |||
| 27 | /** |
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| 28 | * The names of FrontMatter keys that are specially defined for all Documents |
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| 29 | * |
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| 30 | * @var array |
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| 31 | */ |
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| 32 | public static $specialFrontMatterKeys = array( |
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| 33 | 'filename', 'basename' |
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| 34 | ); |
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| 35 | |||
| 36 | protected static $whiteListFunctions = array( |
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| 37 | 'getPermalink', 'getRedirects', 'getTargetFile', 'getName', 'getFilePath', 'getRelativeFilePath', 'getContent', |
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| 38 | 'getExtension', 'getFrontMatter' |
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| 39 | ); |
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| 40 | |||
| 41 | /** |
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| 42 | * An array to keep track of collection or data dependencies used inside of a Twig template. |
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| 43 | * |
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| 44 | * $dataDependencies['collections'] = array() |
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| 45 | * $dataDependencies['data'] = array() |
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| 46 | * |
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| 47 | * @var array |
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| 48 | */ |
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| 49 | protected $dataDependencies; |
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| 50 | |||
| 51 | /** |
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| 52 | * FrontMatter values that can be injected or set after the file has been parsed. Values in this array will take |
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| 53 | * precedence over values in $frontMatter. |
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| 54 | * |
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| 55 | * @var array |
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| 56 | */ |
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| 57 | protected $writableFrontMatter; |
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| 58 | |||
| 59 | /** |
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| 60 | * A list of Front Matter values that should not be returned directly from the $frontMatter array. Values listed |
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| 61 | * here have dedicated functions that handle those Front Matter values and the respective functions should be called |
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| 62 | * instead. |
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| 63 | * |
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| 64 | * @var string[] |
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| 65 | */ |
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| 66 | protected $frontMatterBlacklist; |
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| 67 | |||
| 68 | /** |
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| 69 | * Set to true if the front matter has already been evaluated with variable interpolation. |
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| 70 | * |
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| 71 | * @var bool |
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| 72 | */ |
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| 73 | protected $frontMatterEvaluated; |
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| 74 | |||
| 75 | /** |
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| 76 | * @var Parser |
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| 77 | */ |
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| 78 | protected $frontMatterParser; |
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| 79 | |||
| 80 | /** |
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| 81 | * An array containing the Yaml of the file. |
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| 82 | * |
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| 83 | * @var array |
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| 84 | */ |
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| 85 | protected $frontMatter; |
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| 86 | |||
| 87 | /** |
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| 88 | * Set to true if the body has already been parsed as markdown or any other format. |
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| 89 | * |
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| 90 | * @var bool |
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| 91 | */ |
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| 92 | protected $bodyContentEvaluated; |
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| 93 | |||
| 94 | /** |
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| 95 | * Only the body of the file, i.e. the content. |
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| 96 | * |
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| 97 | * @var string |
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| 98 | */ |
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| 99 | protected $bodyContent; |
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| 100 | |||
| 101 | /** |
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| 102 | * The number of lines that Twig template errors should offset. |
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| 103 | * |
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| 104 | * @var int |
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| 105 | */ |
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| 106 | private $lineOffset; |
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| 107 | |||
| 108 | /** |
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| 109 | * ContentItem constructor. |
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| 110 | * |
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| 111 | * @param string $filePath The path to the file that will be parsed into a ContentItem |
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| 112 | * |
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| 113 | * @throws FileNotFoundException The given file path does not exist |
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| 114 | * @throws IOException The file was not a valid ContentItem. This would meam there was no front matter or |
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| 115 | * no body |
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| 116 | */ |
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| 117 | 132 | public function __construct($filePath) |
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| 124 | |||
| 125 | /** |
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| 126 | * Return the body of the Content Item. |
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| 127 | * |
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| 128 | * @return string |
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| 129 | */ |
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| 130 | abstract public function getContent(); |
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| 131 | |||
| 132 | /** |
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| 133 | * The number of lines that are taken up by FrontMatter and white space. |
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| 134 | * |
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| 135 | * @return int |
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| 136 | */ |
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| 137 | final public function getLineOffset() |
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| 141 | |||
| 142 | /** |
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| 143 | * Get the name of the item, which is just the filename without the extension. |
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| 144 | * |
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| 145 | * @return string |
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| 146 | */ |
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| 147 | 62 | final public function getName() |
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| 151 | |||
| 152 | /** |
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| 153 | * Check whether this object has a reference to a collection or data item. |
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| 154 | * |
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| 155 | * @param string $namespace 'collections' or 'data' |
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| 156 | * @param string $needle |
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| 157 | * |
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| 158 | * @return bool |
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| 159 | */ |
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| 160 | 12 | final public function hasTwigDependency($namespace, $needle) |
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| 166 | |||
| 167 | /** |
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| 168 | * Read the file, and parse its contents. |
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| 169 | */ |
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| 170 | 132 | final public function refreshFileContent() |
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| 222 | |||
| 223 | /** |
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| 224 | * Get all of the references to either DataItems or ContentItems inside of given string. |
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| 225 | * |
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| 226 | * @param string $filter 'collections' or 'data' |
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| 227 | */ |
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| 228 | 120 | private function findTwigDataDependencies($filter) |
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| 237 | |||
| 238 | // |
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| 239 | // Permalink and redirect functionality |
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| 240 | // |
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| 241 | |||
| 242 | 39 | final protected function buildPermalink() |
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| 269 | |||
| 270 | // |
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| 271 | // WritableFrontMatter Implementation |
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| 272 | // |
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| 273 | |||
| 274 | /** |
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| 275 | * {@inheritdoc} |
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| 276 | */ |
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| 277 | 7 | final public function evaluateFrontMatter($variables = null) |
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| 285 | |||
| 286 | /** |
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| 287 | * {@inheritdoc} |
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| 288 | */ |
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| 289 | 29 | final public function getFrontMatter($evaluateYaml = true) |
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| 302 | |||
| 303 | /** |
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| 304 | * {@inheritdoc} |
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| 305 | */ |
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| 306 | 2 | final public function hasExpandedFrontMatter() |
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| 310 | |||
| 311 | /** |
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| 312 | * {@inheritdoc. |
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| 313 | */ |
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| 314 | final public function appendFrontMatter(array $frontMatter) |
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| 321 | |||
| 322 | /** |
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| 323 | * {@inheritdoc. |
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| 324 | */ |
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| 325 | final public function deleteFrontMatter($key) |
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| 334 | |||
| 335 | /** |
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| 336 | * {@inheritdoc. |
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| 337 | */ |
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| 338 | 2 | final public function setFrontMatter(array $frontMatter) |
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| 347 | |||
| 348 | /** |
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| 349 | * Evaluate an array of data for FrontMatter variables. This function will modify the array in place. |
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| 350 | * |
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| 351 | * @param array $yaml An array of data containing FrontMatter variables |
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| 352 | * |
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| 353 | * @throws YamlVariableUndefinedException A FrontMatter variable used does not exist |
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| 354 | */ |
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| 355 | 30 | private function evaluateYaml(&$yaml) |
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| 370 | |||
| 371 | // |
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| 372 | // ArrayAccess Implementation |
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| 373 | // |
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| 374 | |||
| 375 | /** |
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| 376 | * {@inheritdoc} |
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| 377 | */ |
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| 378 | public function offsetSet($offset, $value) |
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| 387 | |||
| 388 | /** |
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| 389 | * {@inheritdoc} |
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| 390 | */ |
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| 391 | 34 | public function offsetExists($offset) |
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| 402 | |||
| 403 | /** |
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| 404 | * {@inheritdoc} |
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| 405 | */ |
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| 406 | public function offsetUnset($offset) |
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| 410 | |||
| 411 | /** |
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| 412 | * {@inheritdoc} |
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| 413 | */ |
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| 414 | 51 | public function offsetGet($offset) |
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| 435 | } |
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| 436 |
Very long variable names usually make code harder to read. It is therefore recommended not to make variable names too verbose.