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 PHPFeature 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 PHPFeature, and based on these observations, apply Extract Interface, too.
1 | <?php |
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25 | class PHPFeature implements FeatureInterface |
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26 | { |
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27 | |||
28 | /** |
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29 | * RegEx pattern that matches the comparison string. |
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30 | * |
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31 | * @since 0.1.0 |
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32 | * |
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33 | * @var string |
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34 | */ |
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35 | const COMPARISON_PATTERN = '/^(?:(<=|lt|<|le|>=|gt|>|ge|=|==|eq|!=|<>|ne))([0-9].*)$/'; |
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36 | |||
37 | /** |
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38 | * Reference to the Configuration object. |
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39 | * |
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40 | * @since 0.1.0 |
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41 | * |
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42 | * @var ConfigInterface |
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43 | */ |
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44 | protected $config; |
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45 | |||
46 | /** |
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47 | * Reference to the Version object. |
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48 | * |
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49 | * @since 0.1.0 |
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50 | * |
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51 | * @var SemanticVersion |
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52 | */ |
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53 | protected $version; |
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54 | |||
55 | /** |
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56 | * Reference to the PHP releases. |
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57 | * |
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58 | * @since 0.2.4 |
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59 | * |
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60 | * @var PHPReleases |
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61 | */ |
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62 | protected $releases; |
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63 | |||
64 | /** |
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65 | * Instantiate a PHPFeature object. |
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66 | * |
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67 | * @since 0.1.0 |
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68 | * |
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69 | * @param SemanticVersion|string|int|null $phpVersion Version of PHP to check the features for. |
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70 | * @param ConfigInterface|null $config Configuration that contains the known features. |
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71 | * |
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72 | * @throws RuntimeException If the PHP version could not be validated. |
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73 | */ |
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74 | 66 | public function __construct($phpVersion = null, ConfigInterface $config = null) |
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98 | |||
99 | /** |
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100 | * Check whether a feature or a collection of features is supported. |
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101 | * |
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102 | * Accepts either a string or an array of strings. Returns true if all the passed-in features are supported, or |
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103 | * false if at least one of them is not. |
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104 | * |
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105 | * @since 0.1.0 |
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106 | * |
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107 | * @param string|array $features What features to check the support of. |
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108 | * |
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109 | * @return bool Whether the set of features as a whole is supported. |
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110 | * @throws InvalidArgumentException If the wrong type of argument is passed in. |
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111 | * @throws RuntimeException If a requirement could not be parsed. |
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112 | */ |
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113 | 23 | public function isSupported($features) |
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136 | |||
137 | /** |
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138 | * Get the minimum required version that supports all of the requested features. |
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139 | * |
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140 | * Accepts either a string or an array of strings. Returns a SemanticVersion object for the version number that is |
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141 | * known to support all the passed-in features, or false if at least one of them is not supported by any known |
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142 | * version. |
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143 | * |
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144 | * @since 0.2.0 |
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145 | * |
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146 | * @param string|array $features What features to check the support of. |
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147 | * |
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148 | * @return SemanticVersion|false SemanticVersion object for the version number that is known to support all the |
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149 | * passed-in features, false if none. |
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150 | * @throws InvalidArgumentException If the wrong type of argument is passed in. |
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151 | * @throws RuntimeException If a requirement could not be parsed. |
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152 | */ |
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153 | 43 | public function getMinimumRequired($features) |
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177 | |||
178 | /** |
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179 | * Check whether a single feature is supported. |
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180 | * |
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181 | * @since 0.1.0 |
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182 | * |
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183 | * @param string $feature The feature to check. |
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184 | * @param string|null $minimumRequired Optional. Minimum required version that supports all features. |
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185 | * |
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186 | * @return bool Whether the requested feature is supported. |
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187 | * @throws RuntimeException If the requirement could not be parsed. |
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188 | */ |
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189 | 66 | protected function checkSupport($feature, &$minimumRequired = null) |
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207 | |||
208 | /** |
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209 | * Check whether a single requirement is met. |
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210 | * |
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211 | * @since 0.1.0 |
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212 | * |
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213 | * @param string $requirement A requirement that is composed of an operator and a version milestone. |
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214 | * @param string|null $minimumRequired Optional. Minimum required version that supports all features. |
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215 | * |
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216 | * @return bool Whether the requirement is met. |
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217 | * @throws RuntimeException If the requirement could not be parsed. |
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218 | */ |
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219 | 64 | protected function checkRequirement($requirement, &$minimumRequired = null) |
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249 | |||
250 | /** |
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251 | * Get the required version for a single requirement. |
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252 | * |
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253 | * @todo The entire algorithm is only an approximation. A 5.2 SemVer library is needed. |
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254 | * |
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255 | * @since 0.2.0 |
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256 | * |
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257 | * @param string $milestone A version milestone that is used to define the requirement. |
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258 | * @param string $operator An operator that gets applied to the milestone. |
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259 | * Possible values: '<=', 'lt', '<', 'le', '>=', 'gt', '>', 'ge', '=', '==', 'eq', '!=', |
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260 | * '<>', 'ne' |
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261 | * |
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262 | * @return string Version string that meets a single requirement. |
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263 | * @throws RuntimeException If the requirement could not be satisfied. |
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264 | * @throws RuntimeException If the NotEqual is used. |
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265 | */ |
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266 | 42 | protected function getRequiredVersion($milestone, $operator) |
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293 | |||
294 | /** |
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295 | * Get a version greater than the milestone. |
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296 | * |
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297 | * @since 0.2.4 |
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298 | * |
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299 | * @param string $milestone A version milestone that is used to define the requirement. |
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300 | * |
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301 | * @return string Version number that meets the requirement. |
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302 | * @throws RuntimeException If the requirement could not be satisfied. |
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303 | */ |
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304 | 4 | View Code Duplication | protected function getGreaterThanVersion($milestone) |
315 | |||
316 | /** |
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317 | * Get a version lesser than the milestone. |
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318 | * |
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319 | * @since 0.2.4 |
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320 | * |
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321 | * @param string $milestone A version milestone that is used to define the requirement. |
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322 | * |
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323 | * @return string Version number that meets the requirement. |
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324 | * @throws RuntimeException If the requirement could not be satisfied. |
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325 | */ |
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326 | 6 | View Code Duplication | protected function getLesserThanVersion($milestone) |
340 | |||
341 | /** |
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342 | * Get a version greater or equal than the milestone. |
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343 | * |
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344 | * @since 0.2.4 |
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345 | * |
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346 | * @param string $milestone A version milestone that is used to define the requirement. |
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347 | * |
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348 | * @return string Version number that meets the requirement. |
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349 | */ |
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350 | 26 | View Code Duplication | protected function getGreaterEqualVersion($milestone) |
365 | |||
366 | /** |
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367 | * Get a version lesser or equal than the milestone. |
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368 | * |
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369 | * @since 0.2.4 |
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370 | * |
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371 | * @param string $milestone A version milestone that is used to define the requirement. |
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372 | * |
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373 | * @return string Version number that meets the requirement. |
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374 | */ |
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375 | 6 | View Code Duplication | protected function getLesserEqualVersion($milestone) |
390 | } |
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391 |