don't use a static ClassLoader instance

- crashes on exit: ros/class_loader#33
- on-demand-unloading works with ros/class_loader#34

Author: rhaschke

Diff for: urdf/src/sensor.cpp

@@ -89,34 +89,28 @@ SensorMap parseSensors(const std::string &xml_string, const SensorParserMap &par
 
 SensorParserMap getSensorParsers(const std::vector<std::string> &allowed)
 {
-  static boost::mutex PARSER_PLUGIN_LOCK;
-  static boost::shared_ptr<pluginlib::ClassLoader<urdf::SensorParser> > PARSER_PLUGIN_LOADER;
-  boost::mutex::scoped_lock _(PARSER_PLUGIN_LOCK);
-
+  pluginlib::ClassLoader<urdf::SensorParser> loader("urdf", "urdf::SensorParser");
   SensorParserMap parserMap;
   try
   {
-    if (!PARSER_PLUGIN_LOADER)
-      PARSER_PLUGIN_LOADER.reset(new pluginlib::ClassLoader<urdf::SensorParser>("urdf", "urdf::SensorParser"));
-
-      const std::vector<std::string> &classes = PARSER_PLUGIN_LOADER->getDeclaredClasses();
-      for (std::size_t i = 0 ; i < classes.size() ; ++i)
-      {
-        // skip this class if not listed in allowed
-        if (!allowed.empty() && std::find(allowed.begin(), allowed.end(), classes[i]) == allowed.end())
-          continue;
-
-        urdf::SensorParserSharedPtr parser;
-        try {
-          parser = PARSER_PLUGIN_LOADER->createInstance(classes[i]);
-        } catch(const pluginlib::PluginlibException& ex) {
-          ROS_ERROR_STREAM("Failed to create sensor parser: " << classes[i] << "\n" << ex.what());
-        }
-        parserMap.insert(std::make_pair(classes[i], parser));
-        ROS_DEBUG_STREAM("added sensor parser: " << classes[i]);
+    const std::vector<std::string> &classes = loader.getDeclaredClasses();
+    for (std::size_t i = 0 ; i < classes.size() ; ++i)
+    {
+      // skip this class if not listed in allowed
+      if (!allowed.empty() && std::find(allowed.begin(), allowed.end(), classes[i]) == allowed.end())
+        continue;
+
+      urdf::SensorParserSharedPtr parser;
+      try {
+        parser = loader.createInstance(classes[i]);
+      } catch(const pluginlib::PluginlibException& ex) {
+        ROS_ERROR_STREAM("Failed to create sensor parser: " << classes[i] << "\n" << ex.what());
       }
-      if (parserMap.empty())
-        ROS_WARN_STREAM("No sensor parsers found");
+      parserMap.insert(std::make_pair(classes[i], parser));
+      ROS_DEBUG_STREAM("added sensor parser: " << classes[i]);
+    }
+    if (parserMap.empty())
+      ROS_WARN_STREAM("No sensor parsers found");
   }
   catch(const pluginlib::PluginlibException& ex)
   {