Shouldn't define static classes as abstract.

New Exception class added (MethodNotImplementedException)

classes/Managed_DataObject.php

@@ -28,7 +28,10 @@ abstract class Managed_DataObject extends Memcached_DataObject
     /**
      * The One True Thingy that must be defined and declared.
      */
-    public static abstract function schemaDef();
+    public static function schemaDef()
+    {
+        throw new MethodNotImplementedException(__METHOD__);
+    }
 
     /**
      * Get an instance by key

lib/iomanager.php

@@ -38,7 +38,9 @@ abstract class IoManager
     /**
      * Factory function to get an appropriate subclass.
      */
-    public abstract static function get();
+    public static function get() {
+        throw new MethodNotImplementedException(__METHOD__);
+    }
 
     /**
      * Tell the i/o queue master if and how we can handle multi-site

lib/methodnotimplementedexception.php

@@ -0,0 +1,50 @@
+<?php
+/**
+ * StatusNet, the distributed open-source microblogging tool
+ *
+ * class for an exception when a method is not implemented
+ *
+ * PHP version 5
+ *
+ * LICENCE: This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category  Exception
+ * @package   StatusNet
+ * @author    Mikael Nordfeldth <mmn@hethane.se>
+ * @copyright 2013 Free Software Foundation, Inc.
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPLv3
+ * @link      http://status.net/
+ */
+
+if (!defined('GNUSOCIAL')) {
+    exit(1);
+}
+
+/**
+ * Class for an exception when a local user is not found by certain criteria
+ *
+ * @category Exception
+ * @package  StatusNet
+ * @author   Mikael Nordfeldth <mmn@hethane.se>
+ * @license  http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPLv3
+ * @link     http://status.net/
+ */
+
+class MethodNotImplementedException extends ServerException
+{
+    public function __construct($method)
+    {
+        parent::__construct(sprintf(_('Method %s not implemented'), $method));
+    }
+}

lib/siteprofile.php

@@ -73,7 +73,10 @@ class SiteProfile
  */
 abstract class SiteProfileSettings
 {
-    abstract static function getSettings();
+    static function getSettings()
+    {
+        throw new MethodNotImplementedException(__METHOD__);
+    }
 
     static function defaultPlugins() {
         return array(