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:
| 1 | <?php |
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| 10 | class DiscussPostRepository |
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| 11 | { |
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| 12 | /** |
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| 13 | * Create a new post instance after a valid validation. |
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| 14 | * |
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| 15 | * @param array $data The data used to create the post. |
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| 16 | * |
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| 17 | * @return \Xetaravel\Models\DiscussPost |
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| 18 | */ |
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| 19 | public static function create(array $data): DiscussPost |
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| 49 | |||
| 50 | /** |
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| 51 | * Find the previous post related to the given post. |
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| 52 | * |
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| 53 | * @param \Xetaravel\Models\DiscussPost $post |
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| 54 | * |
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| 55 | * @return \Xetaravel\Models\DiscussPost|null |
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| 56 | */ |
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| 57 | public static function findPreviousPost(DiscussPost $post) |
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| 65 | } |
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| 66 |
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: