Complex classes like Tree 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 Tree, and based on these observations, apply Extract Interface, too.
1 | <?php |
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36 | class Tree extends NodeObject implements \ArrayAccess, \Countable, \Iterator |
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37 | { |
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38 | /** |
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39 | * @var string |
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40 | */ |
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41 | private $ref; |
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42 | |||
43 | /** |
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44 | * the cursor position |
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45 | * |
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46 | * @var int |
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47 | */ |
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48 | private $position; |
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49 | |||
50 | /** |
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51 | * the tree subject |
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52 | * |
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53 | * @var NodeObject |
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54 | */ |
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55 | private $subject; |
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56 | |||
57 | /** |
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58 | * tree children |
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59 | * |
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60 | * @var array |
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61 | */ |
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62 | private $children = []; |
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63 | |||
64 | /** |
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65 | * tree path children |
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66 | * |
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67 | * @var array |
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68 | */ |
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69 | private $pathChildren = []; |
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70 | |||
71 | /** |
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72 | * the blob of the actual tree |
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73 | * |
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74 | * @var \GitElephant\Objects\NodeObject |
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75 | */ |
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76 | private $blob; |
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77 | |||
78 | /** |
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79 | * static method to generate standalone log |
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80 | * |
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81 | * @param \GitElephant\Repository $repository repo |
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82 | * @param array $outputLines output lines from command.log |
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83 | * |
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84 | * @return \GitElephant\Objects\Tree |
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85 | */ |
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86 | public static function createFromOutputLines(Repository $repository, array $outputLines): \GitElephant\Objects\Tree |
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93 | |||
94 | /** |
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95 | * get the commit properties from command |
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96 | * |
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97 | * @see LsTreeCommand::tree |
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98 | */ |
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99 | 15 | private function createFromCommand(): void |
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105 | |||
106 | /** |
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107 | * Some path examples: |
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108 | * empty string for root |
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109 | * folder1/folder2 |
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110 | * folder1/folder2/filename |
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111 | * |
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112 | * @param \GitElephant\Repository $repository the repository |
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113 | * @param string $ref a treeish reference |
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114 | * @param NodeObject $subject the subject |
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115 | * |
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116 | * @throws \RuntimeException |
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117 | * @throws \Symfony\Component\Process\Exception\RuntimeException |
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118 | * @internal param \GitElephant\Objects\Object|string $treeObject Object instance |
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119 | */ |
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120 | 15 | public function __construct(Repository $repository, $ref = 'HEAD', NodeObject $subject = null) |
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128 | |||
129 | /** |
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130 | * parse the output of a git command showing a ls-tree |
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131 | * |
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132 | * @param array $outputLines output lines |
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133 | */ |
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134 | 15 | private function parseOutputLines(array $outputLines): void |
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144 | |||
145 | /** |
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146 | * @return CallerInterface |
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147 | */ |
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148 | 15 | private function getCaller(): CallerInterface |
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152 | |||
153 | /** |
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154 | * get the current tree parent, null if root |
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155 | * |
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156 | * @return null|string |
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157 | */ |
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158 | public function getParent(): ?string |
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166 | |||
167 | /** |
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168 | * tell if the tree created is the root of the repository |
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169 | * |
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170 | * @return bool |
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171 | */ |
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172 | 15 | public function isRoot(): bool |
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176 | |||
177 | /** |
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178 | * tell if the path given is a blob path |
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179 | * |
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180 | * @return bool |
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181 | */ |
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182 | 15 | public function isBlob(): bool |
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186 | |||
187 | /** |
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188 | * the current tree path is a binary file |
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189 | * |
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190 | * @return bool |
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191 | */ |
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192 | public function isBinary(): bool |
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196 | |||
197 | /** |
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198 | * get binary data |
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199 | * |
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200 | * @throws \RuntimeException |
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201 | * @throws \Symfony\Component\Process\Exception\LogicException |
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202 | * @throws \Symfony\Component\Process\Exception\InvalidArgumentException |
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203 | * @throws \Symfony\Component\Process\Exception\RuntimeException |
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204 | * @return string |
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205 | */ |
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206 | public function getBinaryData(): string |
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212 | |||
213 | /** |
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214 | * Return an array like this |
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215 | * 0 => array( |
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216 | * 'path' => the path to the current element |
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217 | * 'label' => the name of the current element |
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218 | * ), |
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219 | * 1 => array(), |
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220 | * ... |
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221 | * |
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222 | * @return array |
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223 | */ |
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224 | public function getBreadcrumb(): array |
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245 | |||
246 | /** |
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247 | * check if the path is equals to a fullPath |
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248 | * to tell if it's a blob |
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249 | * |
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250 | * @param array $outputLines output lines |
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251 | * |
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252 | * @return mixed |
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253 | */ |
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254 | 15 | private function scanPathsForBlob(array $outputLines): void |
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273 | |||
274 | /** |
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275 | * Reorder children of the tree |
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276 | * Tree first (alphabetically) and then blobs (alphabetically) |
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277 | * |
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278 | * @param \GitElephant\Objects\NodeObject $a the first object |
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279 | * @param \GitElephant\Objects\NodeObject $b the second object |
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280 | * |
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281 | * @return int |
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282 | */ |
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283 | 7 | private static function sortChildren(NodeObject $a, NodeObject $b): int |
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294 | |||
295 | /** |
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296 | * Parse a single line into pieces |
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297 | * |
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298 | * @param string $line a single line output from the git binary |
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299 | * |
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300 | * @return mixed |
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301 | */ |
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302 | 15 | private function parseLine(string $line): void |
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347 | |||
348 | /** |
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349 | * get the last commit message for this tree |
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350 | * |
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351 | * @param string $ref |
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352 | * |
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353 | * @throws \RuntimeException |
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354 | * @return Commit\Message |
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355 | */ |
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356 | public function getLastCommitMessage($ref = 'master'): \GitElephant\Objects\Commit\Message |
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360 | |||
361 | /** |
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362 | * get author of the last commit |
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363 | * |
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364 | * @param string $ref |
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365 | * |
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366 | * @throws \RuntimeException |
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367 | * @return Author |
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368 | */ |
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369 | public function getLastCommitAuthor($ref = 'master'): \GitElephant\Objects\Author |
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373 | |||
374 | /** |
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375 | * get the last commit for a given treeish, for the actual tree |
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376 | * |
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377 | * @param string $ref |
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378 | * |
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379 | * @throws \RuntimeException |
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380 | * @throws \Symfony\Component\Process\Exception\RuntimeException |
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381 | * @return Commit |
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382 | */ |
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383 | public function getLastCommit($ref = 'master'): ?\GitElephant\Objects\Commit |
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392 | |||
393 | /** |
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394 | * get the tree object for this tree |
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395 | * |
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396 | * @return \GitElephant\Objects\NodeObject |
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397 | */ |
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398 | 1 | public function getObject(): ?\GitElephant\Objects\NodeObject |
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402 | |||
403 | /** |
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404 | * Blob getter |
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405 | * |
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406 | * @return \GitElephant\Objects\NodeObject |
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407 | */ |
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408 | 5 | public function getBlob(): \GitElephant\Objects\NodeObject |
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412 | |||
413 | /** |
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414 | * Get Subject |
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415 | * |
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416 | * @return \GitElephant\Objects\NodeObject |
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417 | */ |
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418 | 1 | public function getSubject(): \GitElephant\Objects\NodeObject |
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422 | |||
423 | /** |
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424 | * Get Ref |
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425 | * |
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426 | * @return string |
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427 | */ |
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428 | public function getRef(): string |
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432 | |||
433 | /** |
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434 | * ArrayAccess interface |
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435 | * |
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436 | * @param int $offset offset |
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437 | * |
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438 | * @return bool |
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439 | */ |
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440 | public function offsetExists($offset): bool |
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444 | |||
445 | |||
446 | /** |
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447 | * ArrayAccess interface |
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448 | * |
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449 | * @param int $offset offset |
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450 | * |
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451 | * @return null |
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452 | */ |
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453 | 8 | public function offsetGet($offset) |
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457 | |||
458 | /** |
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459 | * ArrayAccess interface |
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460 | * |
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461 | * @param int $offset offset |
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462 | * @param mixed $value value |
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463 | */ |
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464 | public function offsetSet($offset, $value): void |
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472 | |||
473 | /** |
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474 | * ArrayAccess interface |
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475 | * |
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476 | * @param int $offset offset |
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477 | */ |
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478 | public function offsetUnset($offset): void |
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482 | |||
483 | /** |
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484 | * Countable interface |
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485 | * |
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486 | * @return int |
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487 | */ |
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488 | 4 | public function count(): int |
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492 | |||
493 | /** |
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494 | * Iterator interface |
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495 | * |
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496 | * @return mixed |
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497 | */ |
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498 | 1 | public function current() |
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502 | |||
503 | /** |
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504 | * Iterator interface |
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505 | */ |
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506 | 1 | public function next(): void |
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510 | |||
511 | /** |
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512 | * Iterator interface |
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513 | * |
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514 | * @return int |
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515 | */ |
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516 | public function key(): int |
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520 | |||
521 | /** |
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522 | * Iterator interface |
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523 | * |
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524 | * @return bool |
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525 | */ |
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526 | 1 | public function valid(): bool |
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530 | |||
531 | /** |
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532 | * Iterator interface |
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533 | */ |
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534 | 1 | public function rewind(): void |
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538 | } |
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539 |
Let’s take a look at an example:
In the above example, the authenticate() method works fine as long as you just pass instances of MyUser. However, if you now also want to pass a different implementation of User which does not have a getDisplayName() method, the code will break.
Available Fixes
Change the type-hint for the parameter:
Add an additional type-check:
Add the method to the interface: