Allow many singletons

src/configuration/configuration.php

@@ -9,11 +9,11 @@ class Configuration extends Singleton {
   public $attributes;
 
   public static function set_configuration_path( $path ) {
-    self::$instance = new Configuration( $path );
+    self::set_instance( new self( $path ) );
   }
 
   public static function reset() {
-    self::$instance = null;
+    self::$instances[ self::class ] = null;
   }
 
   public function get( $key, $default = null ) {
@@ -36,7 +36,7 @@ protected function __construct( $path = '.env' ) {
     $configuration = '';
 
     if ( file_exists( $path ) ) {
-      $configuration = @file_get_contents( $path );  
+      $configuration = @file_get_contents( $path );
     }
 
     if ( ! empty( $configuration ) ) {

src/singleton/singleton.php

@@ -3,15 +3,25 @@
 namespace Nectary;
 
 abstract class Singleton {
-  protected static $instance = null;
-  protected function __construct() { }
-
-  protected function __clone() { }
+  protected static $instances = array();
+  protected function __construct() {}
+  protected function __clone() {}
+  public function __wakeup() {
+    throw new Exception( 'Cannot unserialize singleton' );
+  }
 
   public static function get_instance() {
-    if ( ! isset( static::$instance ) ) {
-      static::$instance = new static;
+    $cls = get_called_class(); // late-static-bound class name
+    if ( ! isset( self::$instances[ $cls ] ) ) {
+      self::$instances[ $cls ] = new static;
     }
-    return static::$instance;
+
+    return self::$instances[ $cls ];
+  }
+
+  public static function set_instance( $instance ) {
+    $cls = get_called_class();
+
+    self::$instances[ $cls ] = $instance;
   }
 }