Made ExtensionManager a subclass of MiddlewareManager

scrapy/crawler.py

@@ -4,16 +4,17 @@ from twisted.internet import reactor, defer
 
 from scrapy.core.engine import ExecutionEngine
 from scrapy.core.queue import ExecutionQueue
+from scrapy.extension import ExtensionManager
 from scrapy import log
 from scrapy.utils.ossignal import install_shutdown_handlers, signal_names
 
 
 class Crawler(object):
 
-    def __init__(self, spiders, extensions):
+    def __init__(self, settings, spiders):
         self.configured = False
         self.control_reactor = True
-        self.extensions = extensions
+        self.settings = settings
         self.spiders = spiders
         self.engine = ExecutionEngine(self)
 
@@ -24,12 +25,9 @@ class Crawler(object):
 
         if not log.started:
             log.start()
-        if not self.extensions.loaded:
-            self.extensions.load()
+        self.extensions = ExtensionManager.from_settings(self.settings)
         if not self.spiders.loaded:
             self.spiders.load()
-        log.msg("Enabled extensions: %s" % ", ".join(self.extensions.enabled.iterkeys()),
-            level=log.DEBUG)
 
         self.queue = queue or ExecutionQueue()
         self.engine.configure(self._spider_closed)

scrapy/extension.py

@@ -1,40 +1,16 @@
 """
-This module contains the ExtensionManager  which takes care of loading and
-keeping track of all enabled extensions. It also contains an instantiated
-ExtensionManager (extensions) to be used as singleton.
+The Extension Manager
+
+See documentation in docs/topics/extensions.rst
 """
-from scrapy.exceptions import NotConfigured
-from scrapy.utils.misc import load_object
+from scrapy.middleware import MiddlewareManager
 from scrapy.utils.conf import build_component_list
-from scrapy import log
-from scrapy.conf import settings
 
-class ExtensionManager(object):
+class ExtensionManager(MiddlewareManager):
 
-    def __init__(self):
-        self.loaded = False
-        self.enabled = {}
-        self.disabled = {}
+    component_name = 'extension'
 
-    def load(self):
-        """
-        Load enabled extensions in settings module
-        """
-
-        self.loaded = False
-        self.enabled.clear()
-        self.disabled.clear()
-        extlist = build_component_list(settings['EXTENSIONS_BASE'], \
+    @classmethod
+    def _get_mwlist_from_settings(cls, settings):
+        return build_component_list(settings['EXTENSIONS_BASE'], \
             settings['EXTENSIONS'])
-        for extension_path in extlist:
-            try:
-                cls = load_object(extension_path)
-                self.enabled[cls.__name__] = cls()
-            except NotConfigured, e:
-                self.disabled[cls.__name__] = extension_path
-                if e.args:
-                    log.msg(e)
-        self.loaded = True
-
-    def reload(self):
-        self.load()

scrapy/middleware.py

@@ -35,7 +35,7 @@ class MiddlewareManager(object):
             except NotConfigured, e:
                 if e.args:
                     log.msg(e)
-        enabled = [type(x).__name__ for x in middlewares]
+        enabled = [x.__class__.__name__ for x in middlewares]
         log.msg("Enabled %ss: %s" % (cls.component_name, ", ".join(enabled)), \
             level=log.DEBUG)
         return cls(*middlewares)

scrapy/project.py

@@ -1,8 +1,6 @@
 from scrapy.crawler import Crawler
-from scrapy.extension import ExtensionManager
 from scrapy.utils.misc import load_object
 from scrapy.conf import settings
 
 _spiders = load_object(settings['SPIDER_MANAGER_CLASS'])()
-_extensions = ExtensionManager()
-crawler = Crawler(_spiders, _extensions)
+crawler = Crawler(settings, _spiders)