Complex classes like ElggBatch 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 ElggBatch, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 57 | class ElggBatch |
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| 58 | implements \Iterator { |
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| 59 | |||
| 60 | /** |
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| 61 | * The objects to interator over. |
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| 62 | * |
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| 63 | * @var array |
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| 64 | */ |
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| 65 | private $results = array(); |
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| 66 | |||
| 67 | /** |
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| 68 | * The function used to get results. |
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| 69 | * |
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| 70 | * @var mixed A string, array, or closure, or lamda function |
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| 71 | */ |
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| 72 | private $getter = null; |
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| 73 | |||
| 74 | /** |
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| 75 | * The number of results to grab at a time. |
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| 76 | * |
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| 77 | * @var int |
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| 78 | */ |
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| 79 | private $chunkSize = 25; |
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| 80 | |||
| 81 | /** |
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| 82 | * A callback function to pass results through. |
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| 83 | * |
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| 84 | * @var mixed A string, array, or closure, or lamda function |
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| 85 | */ |
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| 86 | private $callback = null; |
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| 87 | |||
| 88 | /** |
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| 89 | * Start after this many results. |
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| 90 | * |
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| 91 | * @var int |
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| 92 | */ |
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| 93 | private $offset = 0; |
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| 94 | |||
| 95 | /** |
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| 96 | * Stop after this many results. |
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| 97 | * |
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| 98 | * @var int |
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| 99 | */ |
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| 100 | private $limit = 0; |
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| 101 | |||
| 102 | /** |
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| 103 | * Number of processed results. |
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| 104 | * |
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| 105 | * @var int |
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| 106 | */ |
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| 107 | private $retrievedResults = 0; |
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| 108 | |||
| 109 | /** |
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| 110 | * The index of the current result within the current chunk |
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| 111 | * |
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| 112 | * @var int |
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| 113 | */ |
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| 114 | private $resultIndex = 0; |
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| 115 | |||
| 116 | /** |
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| 117 | * The index of the current chunk |
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| 118 | * |
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| 119 | * @var int |
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| 120 | */ |
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| 121 | private $chunkIndex = 0; |
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| 122 | |||
| 123 | /** |
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| 124 | * The number of results iterated through |
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| 125 | * |
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| 126 | * @var int |
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| 127 | */ |
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| 128 | private $processedResults = 0; |
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| 129 | |||
| 130 | /** |
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| 131 | * Is the getter a valid callback |
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| 132 | * |
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| 133 | * @var bool |
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| 134 | */ |
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| 135 | private $validGetter = null; |
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| 136 | |||
| 137 | /** |
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| 138 | * The result of running all entities through the callback function. |
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| 139 | * |
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| 140 | * @var mixed |
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| 141 | */ |
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| 142 | public $callbackResult = null; |
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| 143 | |||
| 144 | /** |
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| 145 | * If false, offset will not be incremented. This is used for callbacks/loops that delete. |
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| 146 | * |
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| 147 | * @var bool |
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| 148 | */ |
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| 149 | private $incrementOffset = true; |
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| 150 | |||
| 151 | /** |
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| 152 | * Entities that could not be instantiated during a fetch |
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| 153 | * |
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| 154 | * @var \stdClass[] |
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| 155 | */ |
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| 156 | private $incompleteEntities = array(); |
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| 157 | |||
| 158 | /** |
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| 159 | * Total number of incomplete entities fetched |
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| 160 | * |
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| 161 | * @var int |
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| 162 | */ |
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| 163 | private $totalIncompletes = 0; |
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| 164 | |||
| 165 | /** |
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| 166 | * Batches operations on any elgg_get_*() or compatible function that supports |
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| 167 | * an options array. |
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| 168 | * |
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| 169 | * Instead of returning all objects in memory, it goes through $chunk_size |
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| 170 | * objects, then requests more from the server. This avoids OOM errors. |
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| 171 | * |
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| 172 | * @param string $getter The function used to get objects. Usually |
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| 173 | * an elgg_get_*() function, but can be any valid PHP callback. |
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| 174 | * @param array $options The options array to pass to the getter function. If limit is |
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| 175 | * not set, 10 is used as the default. In most cases that is not |
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| 176 | * what you want. |
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| 177 | * @param mixed $callback An optional callback function that all results will be passed |
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| 178 | * to upon load. The callback needs to accept $result, $getter, |
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| 179 | * $options. |
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| 180 | * @param int $chunk_size The number of entities to pull in before requesting more. |
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| 181 | * You have to balance this between running out of memory in PHP |
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| 182 | * and hitting the db server too often. |
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| 183 | * @param bool $inc_offset Increment the offset on each fetch. This must be false for |
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| 184 | * callbacks that delete rows. You can set this after the |
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| 185 | * object is created with {@link \ElggBatch::setIncrementOffset()}. |
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| 186 | */ |
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| 187 | public function __construct($getter, $options, $callback = null, $chunk_size = 25, |
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| 232 | |||
| 233 | /** |
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| 234 | * Tell the process that an entity was incomplete during a fetch |
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| 235 | * |
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| 236 | * @param \stdClass $row |
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| 237 | * |
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| 238 | * @access private |
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| 239 | */ |
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| 240 | public function reportIncompleteEntity(\stdClass $row) { |
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| 243 | |||
| 244 | /** |
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| 245 | * Fetches the next chunk of results |
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| 246 | * |
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| 247 | * @return bool |
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| 248 | */ |
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| 249 | private function getNextResultsChunk() { |
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| 334 | |||
| 335 | /** |
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| 336 | * Increment the offset from the original options array? Setting to |
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| 337 | * false is required for callbacks that delete rows. |
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| 338 | * |
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| 339 | * @param bool $increment Set to false when deleting data |
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| 340 | * @return void |
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| 341 | */ |
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| 342 | public function setIncrementOffset($increment = true) { |
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| 345 | |||
| 346 | /** |
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| 347 | * Implements Iterator |
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| 348 | */ |
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| 349 | |||
| 350 | /** |
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| 351 | * PHP Iterator Interface |
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| 352 | * |
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| 353 | * @see Iterator::rewind() |
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| 354 | * @return void |
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| 355 | */ |
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| 356 | public function rewind() { |
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| 367 | |||
| 368 | /** |
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| 369 | * PHP Iterator Interface |
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| 370 | * |
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| 371 | * @see Iterator::current() |
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| 372 | * @return mixed |
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| 373 | */ |
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| 374 | public function current() { |
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| 377 | |||
| 378 | /** |
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| 379 | * PHP Iterator Interface |
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| 380 | * |
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| 381 | * @see Iterator::key() |
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| 382 | * @return int |
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| 383 | */ |
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| 384 | public function key() { |
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| 387 | |||
| 388 | /** |
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| 389 | * PHP Iterator Interface |
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| 390 | * |
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| 391 | * @see Iterator::next() |
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| 392 | * @return mixed |
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| 393 | */ |
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| 394 | public function next() { |
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| 419 | |||
| 420 | /** |
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| 421 | * PHP Iterator Interface |
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| 422 | * |
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| 423 | * @see Iterator::valid() |
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| 424 | * @return bool |
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| 425 | */ |
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| 426 | public function valid() { |
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| 433 | } |
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| 434 |
In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: