Use interface instead of abstract classes for plugins

src/mibew/libs/classes/Mibew/Plugin.php

@@ -1,70 +0,0 @@
-<?php
-/*
- * Copyright 2005-2013 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-namespace Mibew;
-
-/**
- * Base plugin class
- */
-abstract class Plugin
-{
-    /**
-     * Constructor must set this value to true after successful initialization
-     * failures
-     * @var boolean
-     */
-    public $initialized = false;
-
-    /**
-     * An array of plugin configuration
-     * @var array
-     */
-    protected $config = array();
-
-    /**
-     * Returns plugin weight. Weight is used for determine loading order and as
-     * default listner priority.
-     *
-     * @return int Plugin weight
-     */
-    abstract public function getWeight();
-
-    /**
-     * Register listeners
-     *
-     * Event listener take one argument by reference. For example:
-     * <code>
-     *   public function testListener(&$arguments) {
-     *      $arguments['result'] = 'Test string';
-     *   }
-     * </code>
-     */
-    abstract public function registerListeners();
-
-    /**
-     * Returns list of plugin's dependences.
-     *
-     * Each element of dependenses list is a string with a plugin name.
-     * If plugin have no dependenses do not override this method.
-     *
-     * @return array List of plugin's dependences.
-     */
-    public static function getDependences()
-    {
-        return array();
-    }
-}

src/mibew/libs/classes/Mibew/Plugin/Manager.php

@@ -63,22 +63,22 @@ class Manager
      * Loads plugins.
      *
      * The method checks dependences and plugin avaiulability before loading and
-     * invokes Plugin::registerListeners() after loading.
+     * invokes PluginInterface::run() after loading.
      *
      * @param array $plugins_list List of plugins' names and configurations.
      *   For example:
      * <code>
      * $plugins_list = array();
      * $plugins_list[] = array(
-     * 	'name' => 'plugin_name',      // Obligatory value
+     *   'name' => 'plugin_name',     // Obligatory value
-     * 	'config' => array(            // Pass to plugin constructor
+     *   'config' => array(           // Pass to plugin constructor
-     * 		'weight' => 100,
+     *     'weight' => 100,
-     * 		'some_configurable_value' => 'value'
+     *     'some_configurable_value' => 'value'
-     * 	)
+     *   )
      * )
      * </code>
      *
-     * @see Plugin::registerListeners()
+     * @see \Mibew\Plugin\PluginInterface::run()
      */
     public static function loadPlugins($plugins_list)
     {
@@ -116,22 +116,22 @@ class Manager
                 continue;
             }
             // Check if plugin extends abstract 'Plugin' class
-            if ('Mibew\\Plugin' != get_parent_class($plugin_classname)) {
+            if (!in_array('Mibew\\Plugin\\PluginInterface', class_implements($plugin_classname))) {
                 $error_essage = "Plugin class '{$plugin_classname}' does not "
-                    . "extend abstract '\\Mibew\\Plugin' class!";
+                    . "implement '\\Mibew\\Plugin\\PluginInterface' interface!";
                 trigger_error($error_essage, E_USER_WARNING);
                 continue;
             }
 
-            // Check plugin dependences
+            // Check plugin dependencies
-            $plugin_dependences = call_user_func(array(
+            $plugin_dependencies = call_user_func(array(
                 $plugin_classname,
-                'getDependences',
+                'getDependencies',
             ));
-            foreach ($plugin_dependences as $dependence) {
+            foreach ($plugin_dependencies as $dependency) {
-                if (empty(self::$loadedPlugins[$dependence])) {
+                if (empty(self::$loadedPlugins[$dependency])) {
-                    $error_essage = "Plugin '{$dependence}' was not loaded "
+                    $error_essage = "Plugin '{$dependency}' was not loaded "
-                        . "yet, but exists in '{$plugin_name}' dependences list!";
+                        . "yet, but exists in '{$plugin_name}' dependencies list!";
                     trigger_error($error_essage, E_USER_WARNING);
                     continue 2;
                 }
@@ -139,7 +139,7 @@ class Manager
 
             // Add plugin to loading queue
             $plugin_instance = new $plugin_classname($plugin_config);
-            if ($plugin_instance->initialized) {
+            if ($plugin_instance->initialized()) {
                 // Store plugin instance
                 self::$loadedPlugins[$plugin_name] = $plugin_instance;
                 $loading_queue[$plugin_instance->getWeight() . "_" . $offset] = $plugin_instance;
@@ -155,7 +155,7 @@ class Manager
         uksort($loading_queue, 'strnatcmp');
         // Add events and listeners
         foreach ($loading_queue as $plugin) {
-            $plugin->registerListeners();
+            $plugin->run();
         }
     }
 }

src/mibew/libs/classes/Mibew/Plugin/PluginInterface.php

@@ -0,0 +1,59 @@
+<?php
+/*
+ * Copyright 2005-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Mibew\Plugin;
+
+/**
+ * Interface that must be implemented by all plugins.
+ */
+interface PluginInterface
+{
+    /**
+     * Returns plugin weight. Weight is used to determine run priority.
+     *
+     * @return int Plugin weight
+     */
+    public function getWeight();
+
+    /**
+     * Indicates if plugin has been initialized correctly or not.
+     *
+     * A concrete plugin can return false if something go wrong and it cannot be
+     * used but the whole system should works anyway.
+     *
+     * @return boolean
+     */
+    public function initialized();
+
+    /**
+     * This method will be executed when all plugins have been initialized.
+     *
+     * The order based on weights and order in the main configuration file will
+     * be preserved.
+     */
+    public function run();
+
+    /**
+     * Returns list of plugin's dependencies.
+     *
+     * Each element in the list is a string with a plugin name. If plugin have
+     * no dependencies an empty array should be returned.
+     *
+     * @return array List of plugin's dependencies.
+     */
+    public static function getDependencies();
+}