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 Queue 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 Queue, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 16 | final class Queue implements QueueInterface |
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| 17 | { |
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| 18 | /** |
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| 19 | * Maximum millisecond value to use for UTCDateTime creation. |
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| 20 | * |
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| 21 | * @var integer |
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| 22 | */ |
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| 23 | const MONGO_INT32_MAX = PHP_INT_MAX; |
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| 24 | |||
| 25 | /** |
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| 26 | * mongo collection to use for queue. |
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| 27 | * |
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| 28 | * @var \MongoDB\Collection |
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| 29 | */ |
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| 30 | private $collection; |
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| 31 | |||
| 32 | /** |
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| 33 | * Construct queue. |
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| 34 | * |
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| 35 | * @param \MongoDB\Collection|string $collectionOrUrl A MongoCollection instance or the mongo connection url. |
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| 36 | * @param string $db the mongo db name |
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| 37 | * @param string $collection the collection name to use for the queue |
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| 38 | * |
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| 39 | * @throws \InvalidArgumentException $collectionOrUrl, $db or $collection was not a string |
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| 40 | */ |
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| 41 | public function __construct($collectionOrUrl, string $db = null, string $collection = null) |
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| 60 | } |
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| 61 |