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 Plugin 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 Plugin, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 8 | final class Plugin { | 
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| 9 | const PLUGIN_VERSION = '3.5';  | 
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| 10 | |||
| 11 | /**  | 
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| 12 | * @var Plugin The singleton instance.  | 
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| 13 | */  | 
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| 14 | private static $instance;  | 
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| 15 | |||
| 16 | /**  | 
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| 17 | * Instantiates a new Plugin object.  | 
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| 18 | */  | 
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| 19 | 	private function __construct() { | 
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| 22 | |||
| 23 | /**  | 
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| 24 | * Insures we always return the same object.  | 
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| 25 | *  | 
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| 26 | * @return Plugin  | 
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| 27 | */  | 
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| 28 | 	public static function get_instance() { | 
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| 36 | |||
| 37 | /**  | 
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| 38 | * Initialize the plugin.  | 
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| 39 | */  | 
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| 40 | 	public function plugins_loaded() { | 
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| 58 | |||
| 59 | /**  | 
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| 60 | * Check plugin requirements.  | 
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| 61 | *  | 
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| 62 | * @return bool True is fails requirements. False otherwise.  | 
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| 63 | */  | 
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| 64 | 	public function maybe_self_deactivate() { | 
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| 81 | |||
| 82 | /**  | 
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| 83 | * Define all the constants.  | 
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| 84 | */  | 
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| 85 | 	public function constants() { | 
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| 113 | |||
| 114 | /**  | 
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| 115 | * Load all BackUpWordPress functions.  | 
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| 116 | */  | 
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| 117 | 	protected function includes() { | 
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| 118 | |||
| 119 | require_once( HMBKP_PLUGIN_PATH . 'vendor/autoload.php' );  | 
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| 120 | |||
| 121 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-notices.php' );  | 
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| 122 | |||
| 123 | // Load the admin menu  | 
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| 124 | require_once( HMBKP_PLUGIN_PATH . 'admin/menu.php' );  | 
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| 125 | require_once( HMBKP_PLUGIN_PATH . 'admin/actions.php' );  | 
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| 126 | |||
| 127 | // Load Backdrop if necessary.  | 
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| 128 | 		if ( ! class_exists( 'HM_Backdrop_Task' ) ) { | 
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| 129 | require_once( HMBKP_PLUGIN_PATH . 'backdrop/hm-backdrop.php' );  | 
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| 130 | }  | 
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| 131 | |||
| 132 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-requirements.php' );  | 
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| 133 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-requirement.php' );  | 
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| 134 | |||
| 135 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-path.php' );  | 
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| 136 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-excludes.php' );  | 
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| 137 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-site-size.php' );  | 
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| 138 | |||
| 139 | require_once( HMBKP_PLUGIN_PATH . 'classes/backup/class-backup-utilities.php' );  | 
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| 140 | require_once( HMBKP_PLUGIN_PATH . 'classes/backup/class-backup-status.php' );  | 
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| 141 | |||
| 142 | require_once( HMBKP_PLUGIN_PATH . 'classes/backup/class-backup-engine.php' );  | 
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| 143 | |||
| 144 | require_once( HMBKP_PLUGIN_PATH . 'classes/backup/class-backup-engine-database.php' );  | 
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| 145 | require_once( HMBKP_PLUGIN_PATH . 'classes/backup/class-backup-engine-database-mysqldump.php' );  | 
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| 146 | require_once( HMBKP_PLUGIN_PATH . 'classes/backup/class-backup-engine-database-imysqldump.php' );  | 
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| 147 | |||
| 148 | require_once( HMBKP_PLUGIN_PATH . 'classes/backup/class-backup-engine-file.php' );  | 
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| 149 | require_once( HMBKP_PLUGIN_PATH . 'classes/backup/class-backup-engine-file-zip.php' );  | 
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| 150 | require_once( HMBKP_PLUGIN_PATH . 'classes/backup/class-backup-engine-file-zip-archive.php' );  | 
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| 151 | |||
| 152 | require_once( HMBKP_PLUGIN_PATH . 'classes/backup/class-backup.php' );  | 
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| 153 | |||
| 154 | // Load the backup scheduling classes  | 
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| 155 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-scheduled-backup.php' );  | 
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| 156 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-schedules.php' );  | 
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| 157 | |||
| 158 | // Load the core functions  | 
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| 159 | require_once( HMBKP_PLUGIN_PATH . 'functions/core.php' );  | 
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| 160 | require_once( HMBKP_PLUGIN_PATH . 'functions/interface.php' );  | 
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| 161 | |||
| 162 | // Load the services  | 
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| 163 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-services.php' );  | 
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| 164 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-service.php' );  | 
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| 165 | |||
| 166 | // Load the email service  | 
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| 167 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-email-service.php' );  | 
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| 168 | |||
| 169 | // Load the webhook services  | 
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| 170 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-webhook-service.php' );  | 
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| 171 | require_once( HMBKP_PLUGIN_PATH . 'classes/class-wpremote-webhook-service.php' );  | 
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| 172 | |||
| 173 | require_once( HMBKP_PLUGIN_PATH . 'classes/deprecated.php' );  | 
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| 174 | |||
| 175 | // Load the wp cli command  | 
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| 176 | 		if ( defined( 'WP_CLI' ) && WP_CLI ) { | 
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| 177 | include( HMBKP_PLUGIN_PATH . 'classes/class-backupwordpress-wp-cli-command.php' );  | 
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| 178 | }  | 
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| 179 | |||
| 180 | }  | 
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| 181 | |||
| 182 | /**  | 
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| 183 | * Hook into WordPress page lifecycle and execute BackUpWordPress functions.  | 
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| 184 | */  | 
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| 185 | 	public function hooks() { | 
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| 202 | |||
| 203 | /**  | 
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| 204 | * Load the Javascript in the admin.  | 
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| 205 | *  | 
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| 206 | * @param $hook The name of the admin page hook.  | 
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| 207 | */  | 
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| 208 | 	public function scripts( $hook ) { | 
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| 240 | |||
| 241 | /**  | 
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| 242 | * Loads the plugin text domain for translation.  | 
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| 243 | * This setup allows a user to just drop his custom translation files into the WordPress language directory  | 
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| 244 | * Files will need to be in a subdirectory with the name of the textdomain 'backupwordpress'  | 
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| 245 | */  | 
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| 246 | 	public function text_domain() { | 
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| 264 | |||
| 265 | /**  | 
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| 266 | * Determine if we need to run an upgrade routine.  | 
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| 267 | */  | 
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| 268 | 	public function upgrade() { | 
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| 276 | |||
| 277 | /**  | 
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| 278 | * Runs on every admin page load  | 
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| 279 | */  | 
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| 280 | 	public function init() { | 
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| 285 | |||
| 286 | /**  | 
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| 287 | * Generate a unique key.  | 
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| 288 | *  | 
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| 289 | * @return string  | 
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| 290 | */  | 
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| 291 | 	protected function generate_key() { | 
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| 292 | |||
| 293 | $check = apply_filters( 'hmbkp_generate_key', null );  | 
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| 294 | |||
| 295 | 		if ( null !== $check ) { | 
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| 296 | return $check;  | 
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| 297 | }  | 
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| 298 | |||
| 299 | $key = array( ABSPATH, time() );  | 
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| 300 | $constants = array( 'AUTH_KEY', 'SECURE_AUTH_KEY', 'LOGGED_IN_KEY', 'NONCE_KEY', 'AUTH_SALT', 'SECURE_AUTH_SALT', 'LOGGED_IN_SALT', 'NONCE_SALT', 'SECRET_KEY' );  | 
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| 301 | |||
| 302 | 		foreach ( $constants as $constant ) { | 
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| 303 | 			if ( defined( $constant ) ) { | 
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| 304 | $key[] = constant( $constant );  | 
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| 305 | }  | 
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| 306 | }  | 
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| 307 | |||
| 308 | shuffle( $key );  | 
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| 309 | |||
| 310 | return md5( serialize( $key ) );  | 
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| 311 | |||
| 312 | }  | 
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| 313 | |||
| 314 | /**  | 
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| 315 | * Ensure BackUpWordPress is loaded before add-ons, changes the order of the serialized values in the DB field.  | 
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| 316 | */  | 
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| 317 | 	public function load_first() { | 
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| 336 | |||
| 337 | /**  | 
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| 338 | * Function to run when the schedule cron fires.  | 
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| 339 | *  | 
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| 340 | * @param $schedule_id  | 
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| 341 | */  | 
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| 342 | 	public function schedule_hook_run( $schedule_id ) { | 
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| 358 | |||
| 359 | /**  | 
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| 360 | * Enqueue the plugin styles.  | 
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| 361 | *  | 
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| 362 | * @param $hook  | 
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| 363 | */  | 
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| 364 | 	public function styles( $hook ) { | 
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| 379 | |||
| 380 | /**  | 
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| 381 | * Load Intercom and send across user information and server info. Only loaded if the user has opted in.  | 
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| 382 | *  | 
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| 383 | * @param $hook  | 
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| 384 | */  | 
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| 385 | 	public function load_intercom_script() { | 
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| 418 | }  | 
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| 419 | |||
| 425 | 
It seems like the type of the argument is not accepted by the function/method which you are calling.
In some cases, in particular if PHP’s automatic type-juggling kicks in this might be fine. In other cases, however this might be a bug.
We suggest to add an explicit type cast like in the following example: