new file mode 100644
--- /dev/null
+++ b/examples/trac/trac/loader.py
@@ -0,0 +1,140 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2005-2006 Edgewall Software
+# Copyright (C) 2005-2006 Christopher Lenz <cmlenz@gmx.de>
+# All rights reserved.
+#
+# This software is licensed as described in the file COPYING, which
+# you should have received as part of this distribution. The terms
+# are also available at http://trac.edgewall.com/license.html.
+#
+# This software consists of voluntary contributions made by many
+# individuals. For the exact contribution history, see the revision
+# history and logs, available at http://projects.edgewall.com/trac/.
+#
+# Author: Christopher Lenz <cmlenz@gmx.de>
+
+from glob import glob
+import imp
+import os
+import sys
+from trac.config import default_dir
+try:
+    set
+except NameError:
+    from sets import Set as set
+
+try:
+    import pkg_resources
+except ImportError:
+    pkg_resources = None
+
+__all__ = ['load_components']
+
+def load_components(env):
+    loaded_components = []
+    plugins_dirs = [os.path.normcase(os.path.realpath(os.path.join(env.path,
+                                                                  'plugins'))),
+                    default_dir('plugins')]
+
+    # First look for Python source files in the plugins directories, which
+    # simply get imported, thereby registering them with the component manager
+    # if they define any components.
+    for plugins_dir in plugins_dirs:
+        auto_enable = plugins_dir != default_dir('plugins')
+        plugin_files = glob(os.path.join(plugins_dir, '*.py'))
+        for plugin_file in plugin_files:
+            try:
+                plugin_name = os.path.basename(plugin_file[:-3])
+                if plugin_name not in loaded_components:
+                    env.log.debug('Loading file plugin %s from %s' % (plugin_name,
+                                                                 plugin_file))
+                    module = imp.load_source(plugin_name, plugin_file)
+                    loaded_components.append(plugin_name)
+                    if auto_enable and plugin_name + '.*' \
+                            not in env.config['components']:
+                        env.config['components'].set(plugin_name + '.*', 'enabled')
+            except Exception, e:
+                env.log.error('Failed to load plugin from %s', plugin_file,
+                              exc_info=True)
+
+    # If setuptools is installed try to load any eggs from the plugins
+    # directory, and also plugins available on sys.path
+    if pkg_resources is not None:
+        ws = pkg_resources.working_set
+        for plugins_dir in plugins_dirs:
+            ws.add_entry(plugins_dir)
+        pkg_env = pkg_resources.Environment(plugins_dirs + sys.path)
+
+        memo = set()
+        def flatten(dists):
+             for dist in dists:
+                 if dist in memo:
+                     continue
+                 memo.add(dist)
+                 try:
+                     predecessors = ws.resolve([dist.as_requirement()])
+                     for predecessor in flatten(predecessors):
+                         yield predecessor
+                     yield dist
+                 except pkg_resources.DistributionNotFound, e:
+                     env.log.error('Skipping "%s" ("%s" not found)', dist, e)
+                 except pkg_resources.VersionConflict, e:
+                     env.log.error('Skipping "%s" (version conflict: "%s")',
+                                   dist, e)
+
+        for egg in flatten([pkg_env[name][0] for name in pkg_env]):
+            modules = []
+
+            for name in egg.get_entry_map('trac.plugins'):
+                # Load plugins declared via the `trac.plugins` entry point.
+                # This is the only supported option going forward, the
+                # others will be dropped at some point in the future.
+                env.log.debug('Loading egg plugin %s from %s', name,
+                              egg.location)
+                egg.activate()
+                try:
+                    entry_point = egg.get_entry_info('trac.plugins', name)
+                    if entry_point.module_name not in loaded_components:
+                        try:
+                            entry_point.load()
+                        except pkg_resources.DistributionNotFound, e:
+                            env.log.warning('Cannot load plugin %s because it '
+                                            'requires "%s"', name, e)
+                        modules.append(entry_point.module_name)
+                        loaded_components.append(entry_point.module_name)
+                except ImportError, e:
+                    env.log.error('Failed to load plugin %s from %s', name,
+                                  egg.location, exc_info=True)
+
+            else:
+                # Support for pre-entry-point plugins
+                if egg.has_metadata('trac_plugin.txt'):
+                    env.log.debug('Loading plugin %s from %s', name,
+                                  egg.location)
+                    egg.activate()
+                    for modname in egg.get_metadata_lines('trac_plugin.txt'):
+                        module = None
+                        if modname not in loaded_components:
+                            try:
+                                module = __import__(modname)
+                                loaded_components.append(modname)
+                                modules.append(modname)
+                            except ImportError, e:
+                                env.log.error('Component module %s not found',
+                                              modname, exc_info=True)
+
+            if modules:
+                # Automatically enable any components provided by plugins
+                # loaded from the environment plugins directory.
+                if os.path.dirname(egg.location) == plugins_dirs[0]:
+                    for module in modules:
+                        if module + '.*' not in env.config['components']:
+                            env.config['components'].set(module + '.*',
+                                                         'enabled')
+
+    # Load default components
+    from trac.db_default import default_components
+    for module in default_components:
+        if not module in loaded_components:
+            __import__(module)