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 CMB2_REST 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 CMB2_REST, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 14 | class CMB2_REST extends CMB2_Hookup_Base { | 
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                         | 
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| 15 | |||
| 16 | /**  | 
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| 17 | * The current CMB2 REST endpoint version  | 
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| 18 | * @var string  | 
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| 19 | * @since 2.2.4  | 
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| 20 | */  | 
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| 21 | const VERSION = '1';  | 
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| 22 | |||
| 23 | /**  | 
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| 24 | * The CMB2 REST base namespace (v should always be followed by $version)  | 
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| 25 | * @var string  | 
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| 26 | * @since 2.2.4  | 
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| 27 | */  | 
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| 28 | const NAME_SPACE = 'cmb2/v1';  | 
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| 29 | |||
| 30 | /**  | 
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| 31 | * @var CMB2 object  | 
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| 32 | * @since 2.2.4  | 
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| 33 | */  | 
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| 34 | public $cmb;  | 
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| 35 | |||
| 36 | /**  | 
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| 37 | * @var CMB2_REST[] objects  | 
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| 38 | * @since 2.2.4  | 
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| 39 | */  | 
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| 40 | protected static $boxes = array();  | 
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| 41 | |||
| 42 | /**  | 
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| 43 | * @var array Array of cmb ids for each type.  | 
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| 44 | * @since 2.2.4  | 
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| 45 | */  | 
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| 46 | protected static $type_boxes = array(  | 
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| 47 | 'post' => array(),  | 
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| 48 | 'user' => array(),  | 
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| 49 | 'comment' => array(),  | 
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| 50 | 'term' => array(),  | 
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| 51 | );  | 
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| 52 | |||
| 53 | /**  | 
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| 54 | * Array of readable field objects.  | 
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| 55 | * @var CMB2_Field[]  | 
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| 56 | * @since 2.2.4  | 
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| 57 | */  | 
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| 58 | protected $read_fields = array();  | 
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| 59 | |||
| 60 | /**  | 
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| 61 | * Array of editable field objects.  | 
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| 62 | * @var CMB2_Field[]  | 
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| 63 | * @since 2.2.4  | 
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| 64 | */  | 
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| 65 | protected $edit_fields = array();  | 
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| 66 | |||
| 67 | /**  | 
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| 68 | * whether CMB2 object is readable via the rest api.  | 
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| 69 | * @var boolean  | 
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| 70 | */  | 
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| 71 | protected $rest_read = false;  | 
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| 72 | |||
| 73 | /**  | 
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| 74 | * whether CMB2 object is editable via the rest api.  | 
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| 75 | * @var boolean  | 
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| 76 | */  | 
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| 77 | protected $rest_edit = false;  | 
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| 78 | |||
| 79 | /**  | 
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| 80 | * Constructor  | 
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| 81 | *  | 
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| 82 | * @since 2.2.4  | 
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| 83 | *  | 
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| 84 | * @param CMB2 $cmb The CMB2 object to be registered for the API.  | 
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| 85 | */  | 
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| 86 | 	public function __construct( CMB2 $cmb ) { | 
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| 95 | |||
| 96 | /**  | 
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| 97 | * Hooks to register on frontend and backend.  | 
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| 98 | *  | 
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| 99 | * @since 2.2.4  | 
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| 100 | *  | 
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| 101 | * @return void  | 
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| 102 | */  | 
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| 103 | 	public function universal_hooks() { | 
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| 115 | |||
| 116 | /**  | 
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| 117 | * Initiate the CMB2 Boxes and Fields routes  | 
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| 118 | *  | 
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| 119 | * @since 2.2.4  | 
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| 120 | *  | 
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| 121 | * @return void  | 
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| 122 | */  | 
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| 123 | 	public static function init_routes() { | 
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| 132 | |||
| 133 | /**  | 
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| 134 | * Loop through REST boxes and call register_rest_field for each object type.  | 
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| 135 | *  | 
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| 136 | * @since 2.2.4  | 
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| 137 | *  | 
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| 138 | * @return void  | 
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| 139 | */  | 
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| 140 | 	public static function register_cmb2_fields() { | 
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| 191 | |||
| 192 | /**  | 
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| 193 | * Wrapper for register_rest_field.  | 
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| 194 | *  | 
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| 195 | * @since 2.2.4  | 
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| 196 | *  | 
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| 197 | * @param string|array $object_types Object(s) the field is being registered  | 
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| 198 | * to, "post"|"term"|"comment" etc.  | 
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| 199 | * @param string $object_types Canonical object type for callbacks.  | 
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| 200 | *  | 
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| 201 | * @return void  | 
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| 202 | */  | 
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| 203 | 	protected static function register_rest_field( $object_types, $object_type ) { | 
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| 210 | |||
| 211 | /**  | 
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| 212 | * Setup readable and editable fields.  | 
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| 213 | *  | 
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| 214 | * @since 2.2.4  | 
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| 215 | *  | 
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| 216 | * @return void  | 
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| 217 | */  | 
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| 218 | 	protected function declare_read_edit_fields() { | 
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| 236 | |||
| 237 | /**  | 
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| 238 | * Determines if a field is readable based on it's show_in_rest value  | 
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| 239 | * and the box's show_in_rest value.  | 
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| 240 | *  | 
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| 241 | * @since 2.2.4  | 
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| 242 | *  | 
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| 243 | * @param bool $show_in_rest Field's show_in_rest value. Default null.  | 
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| 244 | *  | 
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| 245 | * @return bool Whether field is readable.  | 
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| 246 | */  | 
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| 247 | 	protected function can_read( $show_in_rest ) { | 
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| 256 | |||
| 257 | /**  | 
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| 258 | * Determines if a field is editable based on it's show_in_rest value  | 
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| 259 | * and the box's show_in_rest value.  | 
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| 260 | *  | 
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| 261 | * @since 2.2.4  | 
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| 262 | *  | 
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| 263 | * @param bool $show_in_rest Field's show_in_rest value. Default null.  | 
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| 264 | *  | 
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| 265 | * @return bool Whether field is editable.  | 
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| 266 | */  | 
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| 267 | 	protected function can_edit( $show_in_rest ) { | 
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| 276 | |||
| 277 | /**  | 
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| 278 | * Handler for getting post custom field data.  | 
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| 279 | *  | 
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| 280 | * @since 2.2.4  | 
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| 281 | *  | 
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| 282 | * @param array $object The object data from the response  | 
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| 283 | * @param string $field_name Name of field  | 
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| 284 | * @param WP_REST_Request $request Current request  | 
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| 285 | * @param string $object_type The request object type  | 
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| 286 | *  | 
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| 287 | * @return mixed  | 
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| 288 | */  | 
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| 289 | 	public static function get_post_rest_values( $object, $field_name, $request, $object_type ) { | 
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| 294 | |||
| 295 | /**  | 
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| 296 | * Handler for getting user custom field data.  | 
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| 297 | *  | 
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| 298 | * @since 2.2.4  | 
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| 299 | *  | 
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| 300 | * @param array $object The object data from the response  | 
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| 301 | * @param string $field_name Name of field  | 
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| 302 | * @param WP_REST_Request $request Current request  | 
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| 303 | * @param string $object_type The request object type  | 
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| 304 | *  | 
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| 305 | * @return mixed  | 
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| 306 | */  | 
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| 307 | 	public static function get_user_rest_values( $object, $field_name, $request, $object_type ) { | 
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| 312 | |||
| 313 | /**  | 
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| 314 | * Handler for getting comment custom field data.  | 
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| 315 | *  | 
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| 316 | * @since 2.2.4  | 
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| 317 | *  | 
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| 318 | * @param array $object The object data from the response  | 
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| 319 | * @param string $field_name Name of field  | 
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| 320 | * @param WP_REST_Request $request Current request  | 
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| 321 | * @param string $object_type The request object type  | 
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| 322 | *  | 
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| 323 | * @return mixed  | 
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| 324 | */  | 
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| 325 | 	public static function get_comment_rest_values( $object, $field_name, $request, $object_type ) { | 
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| 330 | |||
| 331 | /**  | 
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| 332 | * Handler for getting term custom field data.  | 
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| 333 | *  | 
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| 334 | * @since 2.2.4  | 
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| 335 | *  | 
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| 336 | * @param array $object The object data from the response  | 
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| 337 | * @param string $field_name Name of field  | 
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| 338 | * @param WP_REST_Request $request Current request  | 
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| 339 | * @param string $object_type The request object type  | 
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| 340 | *  | 
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| 341 | * @return mixed  | 
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| 342 | */  | 
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| 343 | 	public static function get_term_rest_values( $object, $field_name, $request, $object_type ) { | 
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| 348 | |||
| 349 | /**  | 
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| 350 | * Handler for getting custom field data.  | 
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| 351 | *  | 
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| 352 | * @since 2.2.4  | 
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| 353 | *  | 
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| 354 | * @param array $object The object data from the response  | 
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| 355 | * @param WP_REST_Request $request Current request  | 
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| 356 | * @param string $object_type The request object type  | 
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| 357 | * @param string $main_object_type The cmb main object type  | 
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| 358 | *  | 
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| 359 | * @return mixed  | 
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| 360 | */  | 
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| 361 | 	protected static function get_rest_values( $object, $request, $object_type, $main_object_type = 'post' ) { | 
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| 388 | |||
| 389 | /**  | 
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| 390 | * Handler for updating post custom field data.  | 
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| 391 | *  | 
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| 392 | * @since 2.2.4  | 
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| 393 | *  | 
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| 394 | * @param mixed $value The value of the field  | 
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| 395 | * @param object $object The object from the response  | 
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| 396 | * @param string $field_name Name of field  | 
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| 397 | * @param WP_REST_Request $request Current request  | 
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| 398 | * @param string $object_type The request object type  | 
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| 399 | *  | 
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| 400 | * @return bool|int  | 
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| 401 | */  | 
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| 402 | 	public static function update_post_rest_values( $values, $object, $field_name, $request, $object_type ) { | 
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| 407 | |||
| 408 | /**  | 
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| 409 | * Handler for updating user custom field data.  | 
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| 410 | *  | 
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| 411 | * @since 2.2.4  | 
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| 412 | *  | 
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| 413 | * @param mixed $value The value of the field  | 
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| 414 | * @param object $object The object from the response  | 
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| 415 | * @param string $field_name Name of field  | 
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| 416 | * @param WP_REST_Request $request Current request  | 
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| 417 | * @param string $object_type The request object type  | 
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| 418 | *  | 
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| 419 | * @return bool|int  | 
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| 420 | */  | 
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| 421 | 	public static function update_user_rest_values( $values, $object, $field_name, $request, $object_type ) { | 
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| 426 | |||
| 427 | /**  | 
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| 428 | * Handler for updating comment custom field data.  | 
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| 429 | *  | 
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| 430 | * @since 2.2.4  | 
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| 431 | *  | 
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| 432 | * @param mixed $value The value of the field  | 
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| 433 | * @param object $object The object from the response  | 
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| 434 | * @param string $field_name Name of field  | 
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| 435 | * @param WP_REST_Request $request Current request  | 
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| 436 | * @param string $object_type The request object type  | 
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| 437 | *  | 
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| 438 | * @return bool|int  | 
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| 439 | */  | 
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| 440 | 	public static function update_comment_rest_values( $values, $object, $field_name, $request, $object_type ) { | 
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| 445 | |||
| 446 | /**  | 
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| 447 | * Handler for updating term custom field data.  | 
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| 448 | *  | 
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| 449 | * @since 2.2.4  | 
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| 450 | *  | 
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| 451 | * @param mixed $value The value of the field  | 
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| 452 | * @param object $object The object from the response  | 
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| 453 | * @param string $field_name Name of field  | 
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| 454 | * @param WP_REST_Request $request Current request  | 
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| 455 | * @param string $object_type The request object type  | 
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| 456 | *  | 
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| 457 | * @return bool|int  | 
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| 458 | */  | 
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| 459 | 	public static function update_term_rest_values( $values, $object, $field_name, $request, $object_type ) { | 
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| 464 | |||
| 465 | /**  | 
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| 466 | * Handler for updating custom field data.  | 
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| 467 | *  | 
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| 468 | * @since 2.2.4  | 
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| 469 | *  | 
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| 470 | * @param mixed $value The value of the field  | 
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| 471 | * @param object $object The object from the response  | 
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| 472 | * @param WP_REST_Request $request Current request  | 
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| 473 | * @param string $object_type The request object type  | 
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| 474 | * @param string $main_object_type The cmb main object type  | 
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| 475 | *  | 
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| 476 | * @return bool|int  | 
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| 477 | */  | 
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| 478 | 	protected static function update_rest_values( $values, $object, $request, $object_type, $main_object_type = 'post' ) { | 
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| 508 | |||
| 509 | /**  | 
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| 510 | * Loop through box fields and sanitize the values.  | 
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| 511 | *  | 
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| 512 | * @since 2.2.o  | 
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| 513 | *  | 
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| 514 | * @param array $values Array of values being provided.  | 
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| 515 | * @return array Array of updated/sanitized values.  | 
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| 516 | */  | 
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| 517 | 	public function sanitize_box_values( array $values ) { | 
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| 530 | |||
| 531 | /**  | 
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| 532 | * Handles returning a sanitized field value.  | 
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| 533 | *  | 
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| 534 | * @since 2.2.4  | 
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| 535 | *  | 
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| 536 | * @param array $values Array of values being provided.  | 
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| 537 | * @param string $field_id The id of the field to update.  | 
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| 538 | *  | 
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| 539 | * @return mixed The results of saving/sanitizing a field value.  | 
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| 540 | */  | 
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| 541 | 	protected function sanitize_field_value( array $values, $field_id ) { | 
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| 561 | |||
| 562 | /**  | 
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| 563 | * Handles returning a sanitized group field value.  | 
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| 564 | *  | 
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| 565 | * @since 2.2.4  | 
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| 566 | *  | 
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| 567 | * @param array $values Array of values being provided.  | 
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| 568 | * @param CMB2_Field $field CMB2_Field object.  | 
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| 569 | *  | 
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| 570 | * @return mixed The results of saving/sanitizing the group field value.  | 
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| 571 | */  | 
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| 572 | 	protected function sanitize_group_value( array $values, CMB2_Field $field ) { | 
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| 582 | |||
| 583 | /**  | 
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| 584 | * Filter whether a meta key is protected.  | 
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| 585 | *  | 
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| 586 | * @since 2.2.4  | 
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| 587 | *  | 
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| 588 | * @param bool $protected Whether the key is protected. Default false.  | 
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| 589 | * @param string $meta_key Meta key.  | 
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| 590 | * @param string $meta_type Meta type.  | 
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| 591 | */  | 
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| 592 | 	public function is_protected_meta( $protected, $meta_key, $meta_type ) { | 
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| 599 | |||
| 600 | 	protected static function get_object_id( $object, $object_type = 'post' ) { | 
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| 621 | |||
| 622 | 	public function field_can_read( $field_id, $return_object = false ) { | 
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| 625 | |||
| 626 | 	public function field_can_edit( $field_id, $return_object = false ) { | 
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| 629 | |||
| 630 | 	protected function field_can( $type = 'read_fields', $field_id, $return_object = false ) { | 
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| 637 | |||
| 638 | /**  | 
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| 639 | * Get a CMB2_REST instance object from the registry by a CMB2 id.  | 
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| 640 | *  | 
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| 641 | * @since 2.2.4  | 
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| 642 | *  | 
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| 643 | * @param string $cmb_id CMB2 config id  | 
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| 644 | *  | 
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| 645 | * @return CMB2_REST|false The CMB2_REST object or false.  | 
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| 646 | */  | 
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| 647 | 	public static function get_rest_box( $cmb_id ) { | 
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| 650 | |||
| 651 | /**  | 
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| 652 | * Remove a CMB2_REST instance object from the registry.  | 
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| 653 | *  | 
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| 654 | * @since 2.2.4  | 
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| 655 | *  | 
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| 656 | * @param string $cmb_id A CMB2 instance id.  | 
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| 657 | */  | 
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| 658 | 	public static function remove( $cmb_id ) { | 
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| 663 | |||
| 664 | /**  | 
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| 665 | * Retrieve all CMB2_REST instances from the registry.  | 
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| 666 | *  | 
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| 667 | * @since 2.2.4  | 
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| 668 | * @return CMB2[] Array of all registered CMB2_REST instances.  | 
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| 669 | */  | 
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| 670 | 	public static function get_all() { | 
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| 673 | |||
| 674 | /**  | 
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| 675 | * Checks if given value is readable.  | 
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| 676 | *  | 
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| 677 | * Value is considered readable if it is not empty and if it does not match the editable blacklist.  | 
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| 678 | *  | 
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| 679 | * @since 2.2.4  | 
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| 680 | *  | 
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| 681 | * @param mixed $value Value to check.  | 
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| 682 | *  | 
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| 683 | * @return boolean Whether value is considered readable.  | 
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| 684 | */  | 
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| 685 | 	public static function is_readable( $value ) { | 
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| 692 | |||
| 693 | /**  | 
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| 694 | * Checks if given value is editable.  | 
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| 695 | *  | 
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| 696 | * Value is considered editable if matches the editable whitelist.  | 
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| 697 | *  | 
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| 698 | * @since 2.2.4  | 
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| 699 | *  | 
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| 700 | * @param mixed $value Value to check.  | 
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| 701 | *  | 
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| 702 | * @return boolean Whether value is considered editable.  | 
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| 703 | */  | 
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| 704 | 	public static function is_editable( $value ) { | 
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| 710 | |||
| 711 | /**  | 
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| 712 | * Magic getter for our object.  | 
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| 713 | *  | 
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| 714 | * @param string $field  | 
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| 715 | * @throws Exception Throws an exception if the field is invalid.  | 
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| 716 | *  | 
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| 717 | * @return mixed  | 
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| 718 | */  | 
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| 719 | 	public function __get( $field ) { | 
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| 730 | |||
| 731 | }  | 
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| 732 | 
You can fix this by adding a namespace to your class:
When choosing a vendor namespace, try to pick something that is not too generic to avoid conflicts with other libraries.