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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| 8 | class PostType extends Component  | 
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| 9 | { | 
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| 10 | use Columns;  | 
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| 11 | |||
| 12 | const CUSTOM_KEYS = [  | 
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| 13 | 'columns', 'menu_name', 'plural', 'single', 'slug',  | 
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| 14 | ];  | 
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| 15 | |||
| 16 | const POST_TYPE_DEFAULTS = [  | 
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| 17 | 'capability_type' => 'post',  | 
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| 18 | 'columns' => [],  | 
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| 19 | 'has_archive' => false,  | 
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| 20 | 'hierarchical' => false,  | 
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| 21 | 'labels' => [],  | 
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| 22 | 'map_meta_cap' => true,  | 
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| 23 | 'menu_icon' => null,  | 
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| 24 | 'menu_name' => '',  | 
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| 25 | 'menu_position' => 5,  | 
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| 26 | 'plural' => '',  | 
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| 27 | 'public' => true,  | 
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| 28 | 'query_var' => true,  | 
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| 29 | 'rewrite' => true,  | 
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| 30 | 'show_in_menu' => true,  | 
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| 31 | 'show_ui' => true,  | 
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| 32 | 'single' => '',  | 
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| 33 | 'slug' => '',  | 
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| 34 | 'supports' => ['title', 'editor', 'thumbnail'],  | 
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| 35 | 'taxonomies' => [],  | 
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| 36 | ];  | 
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| 37 | |||
| 38 | /**  | 
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| 39 | * @var array  | 
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| 40 | */  | 
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| 41 | public $types = [];  | 
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| 42 | |||
| 43 | /**  | 
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| 44 | 	 * {@inheritdoc} | 
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| 45 | */  | 
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| 46 | public function init()  | 
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| 54 | |||
| 55 | /**  | 
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| 56 | * @return void  | 
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| 57 | * @action init  | 
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| 58 | */  | 
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| 59 | public function register()  | 
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| 69 | |||
| 70 | /**  | 
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| 71 | 	 * {@inheritdoc} | 
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| 72 | */  | 
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| 73 | protected function normalize()  | 
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| 82 | |||
| 83 | /**  | 
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| 84 | * @param mixed $labels  | 
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| 85 | * @return array  | 
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| 86 | */  | 
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| 87 | protected function normalizeLabels( $labels, array $args )  | 
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| 91 | |||
| 92 | /**  | 
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| 93 | * @param string $menuname  | 
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| 94 | * @return string  | 
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| 95 | */  | 
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| 96 | protected function normalizeMenuName( $menuname, array $args )  | 
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| 102 | |||
| 103 | /**  | 
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| 104 | * @param mixed $rewrite  | 
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| 105 | * @return mixed  | 
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| 106 | */  | 
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| 107 | protected function normalizeRewrite( $rewrite, array $args )  | 
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| 117 | |||
| 118 | /**  | 
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| 119 | * @return array  | 
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| 120 | */  | 
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| 121 | protected function setLabels( array $args )  | 
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| 138 | }  | 
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| 139 |