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 ChangelogEntry 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 ChangelogEntry, and based on these observations, apply Extract Interface, too.
1 | <?php // phpcs:ignore WordPress.Files.FileName.NotHyphenatedLowercase |
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19 | class ChangelogEntry implements JsonSerializable { |
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20 | |||
21 | /** |
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22 | * Entry version. |
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23 | * |
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24 | * @var string |
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25 | */ |
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26 | protected $version; |
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27 | |||
28 | /** |
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29 | * Entry link. |
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30 | * |
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31 | * @var string|null |
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32 | */ |
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33 | protected $link = null; |
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34 | |||
35 | /** |
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36 | * Entry timestamp. |
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37 | * |
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38 | * @var DateTime|null |
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39 | */ |
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40 | protected $timestamp; |
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41 | |||
42 | /** |
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43 | * Content before the changes themselves. |
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44 | * |
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45 | * @var string |
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46 | */ |
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47 | protected $prologue = ''; |
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48 | |||
49 | /** |
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50 | * Content after the changes themselves. |
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51 | * |
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52 | * @var string |
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53 | */ |
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54 | protected $epilogue = ''; |
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55 | |||
56 | /** |
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57 | * Changes. |
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58 | * |
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59 | * @var ChangeEntry[] |
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60 | */ |
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61 | protected $changes = array(); |
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62 | |||
63 | /** |
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64 | * Constructor. |
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65 | * |
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66 | * @param string $version Version for the new entry. |
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67 | * @param array $data Data for other entry fields. Keys correspond to the setters, e.g. key 'link' calls `setLink()`. |
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68 | * @throws InvalidArgumentException If an argument is invalid. |
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69 | */ |
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70 | View Code Duplication | public function __construct( $version, array $data = array() ) { |
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81 | |||
82 | /** |
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83 | * Get the version. |
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84 | * |
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85 | * @return string |
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86 | */ |
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87 | public function getVersion() { |
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90 | |||
91 | /** |
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92 | * Set the version. |
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93 | * |
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94 | * @param string $version Version to set. |
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95 | * @returns $this |
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96 | * @throws InvalidArgumentException If an argument is invalid. |
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97 | */ |
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98 | public function setVersion( $version ) { |
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106 | |||
107 | /** |
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108 | * Get the link. |
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109 | * |
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110 | * @return string|null |
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111 | */ |
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112 | public function getLink() { |
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115 | |||
116 | /** |
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117 | * Set the link. |
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118 | * |
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119 | * @param string|null $link Link to set. |
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120 | * @returns $this |
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121 | * @throws InvalidArgumentException If an argument is invalid. |
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122 | */ |
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123 | public function setLink( $link ) { |
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135 | |||
136 | /** |
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137 | * Get the timestamp. |
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138 | * |
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139 | * The timestamp may be null, which should be interpreted as "unreleased". |
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140 | * |
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141 | * @return DateTime|null |
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142 | */ |
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143 | public function getTimestamp() { |
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146 | |||
147 | /** |
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148 | * Set the timestamp. |
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149 | * |
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150 | * The timestamp may be null, which should be interpreted as "unreleased". |
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151 | * |
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152 | * @param DateTime|string|null $timestamp Timestamp to set. |
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153 | * @returns $this |
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154 | * @throws InvalidArgumentException If an argument is invalid. |
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155 | */ |
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156 | View Code Duplication | public function setTimestamp( $timestamp ) { |
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167 | |||
168 | /** |
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169 | * Get the prologue content. |
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170 | * |
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171 | * @return string |
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172 | */ |
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173 | public function getPrologue() { |
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176 | |||
177 | /** |
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178 | * Set the prologue content. |
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179 | * |
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180 | * @param string $prologue Prologue content to set. |
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181 | * @return $this |
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182 | */ |
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183 | public function setPrologue( $prologue ) { |
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187 | |||
188 | /** |
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189 | * Get the epilogue content. |
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190 | * |
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191 | * @return string |
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192 | */ |
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193 | public function getEpilogue() { |
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196 | |||
197 | /** |
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198 | * Set the epilogue content. |
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199 | * |
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200 | * @param string $epilogue Epilogue content to set. |
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201 | * @return $this |
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202 | */ |
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203 | public function setEpilogue( $epilogue ) { |
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207 | |||
208 | /** |
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209 | * Get the list of changes. |
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210 | * |
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211 | * @return ChangeEntry[] |
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212 | */ |
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213 | public function getChanges() { |
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216 | |||
217 | /** |
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218 | * Set the list of changes. |
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219 | * |
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220 | * This replaces all existing changes. The caller is responsible |
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221 | * for making sure the changes are sorted properly. |
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222 | * |
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223 | * @param ChangeEntry[] $changes Changes. |
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224 | * @return $this |
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225 | * @throws InvalidArgumentException If an argument is invalid. |
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226 | */ |
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227 | View Code Duplication | public function setChanges( array $changes ) { |
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237 | |||
238 | /** |
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239 | * Add a new change. |
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240 | * |
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241 | * The new change is inserted before the first existing change where |
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242 | * `ChangeEntry::compare()` says the existing change should come after. |
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243 | * |
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244 | * @param ChangeEntry $change New change. |
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245 | * @param array $compareconfig Comparison config, see `ChangeEntry::compare()`. |
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246 | * @return $this |
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247 | */ |
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248 | public function insertChange( ChangeEntry $change, $compareconfig = array() ) { |
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258 | |||
259 | /** |
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260 | * Append a new change. |
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261 | * |
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262 | * @param ChangeEntry $change New change. |
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263 | * @return $this |
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264 | */ |
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265 | public function appendChange( ChangeEntry $change ) { |
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269 | |||
270 | /** |
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271 | * Get the changes grouped by subheading. |
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272 | * |
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273 | * @param string|null $subheading Subheading to retrieve. |
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274 | * @return ChangeEntry[]|ChangeEntry[][] An array of changes with the |
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275 | * heading if `$subheading` was passed, or an array keyed by subheading of |
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276 | * arrays of changes if it was null. |
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277 | */ |
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278 | public function getChangesBySubheading( $subheading = null ) { |
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288 | |||
289 | /** |
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290 | * Return data for serializing to JSON. |
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291 | * |
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292 | * @return array |
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293 | */ |
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294 | public function jsonSerialize() { |
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305 | |||
306 | /** |
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307 | * Unserialize from JSON. |
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308 | * |
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309 | * @param array $data JSON data as returned by self::jsonSerialize(). |
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310 | * @return static |
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311 | * @throws InvalidArgumentException If the data is invalid. |
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312 | */ |
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313 | public static function jsonUnserialize( $data ) { |
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329 | |||
330 | } |
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331 |