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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| 9 | class User_Meta_Container extends Container { |
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| 10 | protected $user_id; |
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| 11 | |||
| 12 | public $settings = array( |
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| 13 | 'show_on' => array( |
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| 14 | 'role' => array(), |
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| 15 | ), |
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| 16 | 'show_for' => array( |
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| 17 | 'relation' => 'AND', |
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| 18 | 'edit_users', |
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| 19 | ), |
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| 20 | ); |
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| 21 | |||
| 22 | /** |
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| 23 | * Create a new container |
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| 24 | * |
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| 25 | * @param string $unique_id Unique id of the container |
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| 26 | * @param string $title title of the container |
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| 27 | * @param string $type Type of the container |
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| 28 | **/ |
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| 29 | public function __construct( $unique_id, $title, $type ) { |
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| 36 | |||
| 37 | /** |
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| 38 | * Bind attach() and save() to the appropriate WordPress actions. |
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| 39 | **/ |
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| 40 | public function init() { |
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| 45 | |||
| 46 | /** |
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| 47 | * Checks whether the current request is valid |
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| 48 | * |
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| 49 | * @return bool |
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| 50 | **/ |
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| 51 | public function is_valid_save( $user_id = 0 ) { |
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| 62 | |||
| 63 | /** |
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| 64 | * Perform save operation after successful is_valid_save() check. |
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| 65 | * The call is propagated to all fields in the container. |
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| 66 | * |
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| 67 | * @param int $user_id ID of the user against which save() is ran |
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| 68 | **/ |
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| 69 | View Code Duplication | public function save( $user_id ) { |
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| 82 | |||
| 83 | /** |
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| 84 | * Perform checks whether the container should be attached during the current request |
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| 85 | * |
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| 86 | * @return bool True if the container is allowed to be attached |
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| 87 | **/ |
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| 88 | public function is_valid_attach_for_request() { |
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| 95 | |||
| 96 | /** |
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| 97 | * Check container attachment rules against object id |
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| 98 | * |
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| 99 | * @param int $object_id |
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| 100 | * @return bool |
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| 101 | **/ |
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| 102 | public function is_valid_attach_for_object( $object_id = null ) { |
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| 130 | |||
| 131 | /** |
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| 132 | * Add the container to the user |
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| 133 | **/ |
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| 134 | public function attach() { |
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| 139 | |||
| 140 | /** |
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| 141 | * Whether we're on the user profile page |
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| 142 | **/ |
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| 143 | public function is_profile_page() { |
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| 148 | |||
| 149 | /** |
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| 150 | * Perform checks whether the container should be seen for the currently logged in user |
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| 151 | * |
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| 152 | * @return bool True if the current user is allowed to see the container |
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| 153 | **/ |
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| 154 | public function is_valid_show_for() { |
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| 175 | |||
| 176 | /** |
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| 177 | * Output the container markup |
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| 178 | **/ |
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| 179 | public function render( $user_profile = null ) { |
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| 193 | |||
| 194 | /** |
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| 195 | * Set the user ID the container will operate with. |
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| 196 | * |
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| 197 | * @param int $user_id |
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| 198 | **/ |
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| 199 | public function set_user_id( $user_id ) { |
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| 203 | |||
| 204 | /** |
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| 205 | * Validate and parse the show_for logic rules. |
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| 206 | * |
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| 207 | * @param array $show_for |
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| 208 | * @return array |
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| 209 | */ |
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| 210 | protected function parse_show_for( $show_for ) { |
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| 237 | |||
| 238 | /** |
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| 239 | * COMMON USAGE METHODS |
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| 240 | */ |
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| 241 | |||
| 242 | /** |
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| 243 | * Show the container only on users who have the $role role. |
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| 244 | * |
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| 245 | * @param string $role |
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| 246 | * @return object $this |
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| 247 | **/ |
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| 248 | public function show_on_user_role( $role ) { |
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| 253 | |||
| 254 | /** |
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| 255 | * Show the container only for users who have either capabilities or roles setup |
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| 256 | * |
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| 257 | * @param array $show_for |
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| 258 | * @return object $this |
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| 259 | **/ |
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| 260 | public function show_for( $show_for ) { |
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| 265 | } |
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| 266 |
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: