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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| 13 | class Jetpack_Memberships { | 
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| 14 | /**  | 
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| 15 | * CSS class prefix to use in the styling.  | 
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| 16 | *  | 
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| 17 | * @var string  | 
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| 18 | */  | 
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| 19 | public static $css_classname_prefix = 'jetpack-memberships';  | 
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| 20 | /**  | 
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| 21 | * Our CPT type for the product (plan).  | 
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| 22 | *  | 
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| 23 | * @var string  | 
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| 24 | */  | 
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| 25 | public static $post_type_plan = 'jp_mem_plan';  | 
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| 26 | /**  | 
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| 27 | * Option that will store currently set up account (Stripe etc) id for memberships.  | 
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| 28 | *  | 
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| 29 | * @var string  | 
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| 30 | */  | 
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| 31 | public static $connected_account_id_option_name = 'jetpack-memberships-connected-account-id';  | 
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| 32 | /**  | 
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| 33 | * Button block type to use.  | 
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| 34 | *  | 
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| 35 | * @var string  | 
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| 36 | */  | 
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| 37 | private static $button_block_name = 'recurring-payments';  | 
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| 38 | |||
| 39 | /**  | 
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| 40 | * These are defaults for wp_kses ran on the membership button.  | 
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| 41 | *  | 
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| 42 | * @var array  | 
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| 43 | */  | 
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| 44 | private static $tags_allowed_in_the_button = array( 'br' => array() );  | 
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| 45 | |||
| 46 | /**  | 
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| 47 | * The minimum required plan for this Gutenberg block.  | 
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| 48 | *  | 
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| 49 | * @var string Plan slug  | 
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| 50 | */  | 
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| 51 | private static $required_plan;  | 
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| 52 | |||
| 53 | /**  | 
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| 54 | * Track recurring payments block registration.  | 
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| 55 | *  | 
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| 56 | * @var boolean True if block registration has been executed.  | 
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| 57 | */  | 
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| 58 | private static $has_registered_block = false;  | 
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| 59 | |||
| 60 | /**  | 
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| 61 | * Classic singleton pattern  | 
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| 62 | *  | 
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| 63 | * @var Jetpack_Memberships  | 
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| 64 | */  | 
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| 65 | private static $instance;  | 
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| 66 | |||
| 67 | /**  | 
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| 68 | * Jetpack_Memberships constructor.  | 
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| 69 | */  | 
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| 70 | 	private function __construct() {} | 
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| 71 | |||
| 72 | /**  | 
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| 73 | * The actual constructor initializing the object.  | 
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| 74 | *  | 
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| 75 | * @return Jetpack_Memberships  | 
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| 76 | */  | 
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| 77 | View Code Duplication | 	public static function get_instance() { | 
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| 87 | /**  | 
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| 88 | * Get the map that defines the shape of CPT post. keys are names of fields and  | 
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| 89 | * 'meta' is the name of actual WP post meta field that corresponds.  | 
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| 90 | *  | 
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| 91 | * @return array  | 
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| 92 | */  | 
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| 93 | 	private static function get_plan_property_mapping() { | 
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| 105 | |||
| 106 | /**  | 
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| 107 | * Inits further hooks on init hook.  | 
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| 108 | */  | 
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| 109 | 	private function register_init_hook() { | 
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| 113 | |||
| 114 | /**  | 
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| 115 | * Actual hooks initializing on init.  | 
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| 116 | */  | 
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| 117 | 	public function init_hook_action() { | 
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| 122 | |||
| 123 | /**  | 
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| 124 | * Sets up the custom post types for the module.  | 
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| 125 | */  | 
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| 126 | 	private function setup_cpts() { | 
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| 159 | |||
| 160 | /**  | 
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| 161 | * Allows custom post types to be used by REST API.  | 
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| 162 | *  | 
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| 163 | * @param array $post_types - other post types.  | 
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| 164 | *  | 
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| 165 | * @see hook 'rest_api_allowed_post_types'  | 
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| 166 | * @return array  | 
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| 167 | */  | 
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| 168 | 	public function allow_rest_api_types( $post_types ) { | 
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| 173 | |||
| 174 | /**  | 
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| 175 | * Allows custom meta fields to sync.  | 
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| 176 | *  | 
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| 177 | * @param array $post_meta - previously changet post meta.  | 
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| 178 | *  | 
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| 179 | * @return array  | 
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| 180 | */  | 
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| 181 | 	public function allow_sync_post_meta( $post_meta ) { | 
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| 188 | |||
| 189 | /**  | 
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| 190 | * This returns meta attribute of passet array.  | 
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| 191 | * Used for array functions.  | 
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| 192 | *  | 
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| 193 | * @param array $map - stuff.  | 
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| 194 | *  | 
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| 195 | * @return mixed  | 
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| 196 | */  | 
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| 197 | 	public function return_meta( $map ) { | 
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| 200 | /**  | 
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| 201 | * Callback that parses the membership purchase shortcode.  | 
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| 202 | *  | 
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| 203 | * @param array $attrs - attributes in the shortcode. `id` here is the CPT id of the plan.  | 
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| 204 | *  | 
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| 205 | * @return string|void  | 
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| 206 | */  | 
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| 207 | 	public function render_button( $attrs ) { | 
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| 280 | |||
| 281 | /**  | 
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| 282 | * Get current blog id.  | 
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| 283 | *  | 
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| 284 | * @return int  | 
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| 285 | */  | 
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| 286 | 	public static function get_blog_id() { | 
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| 293 | |||
| 294 | /**  | 
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| 295 | * Get the id of the connected payment acount (Stripe etc).  | 
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| 296 | *  | 
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| 297 | * @return int|void  | 
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| 298 | */  | 
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| 299 | 	public static function get_connected_account_id() { | 
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| 302 | |||
| 303 | /**  | 
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| 304 | * Whether Recurring Payments are enabled.  | 
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| 305 | *  | 
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| 306 | * @return bool  | 
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| 307 | */  | 
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| 308 | 	public static function is_enabled_jetpack_recurring_payments() { | 
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| 322 | |||
| 323 | /**  | 
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| 324 | * Register the Recurring Payments Gutenberg block  | 
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| 325 | */  | 
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| 326 | 	public function register_gutenberg_block() { | 
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| 354 | }  | 
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| 355 | Jetpack_Memberships::get_instance();  | 
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| 356 |