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.