🔖 Version 1.0.0-beta

Civi/Mailinglistsync/Singleton.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Civi\Mailinglistsync;
+
+use Civi\Mailinglistsync\Exceptions\ContactSyncException;
+use Civi\Mailinglistsync\Exceptions\MailinglistException;
+use CRM_Mailinglistsync_ExtensionUtil as E;
+
+trait Singleton {
+
+  /**
+   * Singleton instance.
+   */
+  private static $instance;
+
+  /**
+   * Protect singleton from being instantiated.
+   */
+  protected function __construct() {}
+
+  /**
+   * Protect singleton from being cloned.
+   */
+  protected function __clone() {}
+
+  /**
+   * Protect unserialize method to prevent cloning of the instance.
+   * @throws \Exception
+   */
+  public function __wakeup()
+  {
+    throw new ContactSyncException(
+      "Cannot unserialize a singleton.",
+      MailinglistException::ERROR_CODE_UNSERIALIZE_SINGLETON
+    );
+  }
+
+  /**
+   * Returns the singleton instance.
+   *
+   * @return self
+   */
+  public static function getInstance(): self
+  {
+    if (!self::$instance) {
+      self::$instance = new self();
+    }
+    return self::$instance;
+  }
+}