Load kombu root module lazily

kombu/__init__.py

@@ -4,10 +4,56 @@ __version__ = ".".join(map(str, VERSION[0:3])) + "".join(VERSION[3:])
 __author__ = "Ask Solem"
 __contact__ = "ask@celeryproject.org"
 __homepage__ = "http://github.com/ask/kombu/"
-__docformat__ = "restructuredtext"
+__docformat__ = "restructuredtext en"
 
 import os
+import sys
 if not os.environ.get("KOMBU_NO_EVAL", False):
-    from kombu.connection import BrokerConnection
-    from kombu.entity import Exchange, Queue
-    from kombu.messaging import Consumer, Producer
+    # Lazy loading.
+    # - See werkzeug/__init__.py for the rationale behind this.
+    from types import ModuleType
+
+    all_by_module = {
+            "kombu.connection": ["BrokerConnection"],
+            "kombu.entity": ["Exchange", "Queue"],
+            "kombu.messaging": ["Consumer", "Producer"],
+    }
+
+    object_origins = {}
+    for module, items in all_by_module.iteritems():
+        for item in items:
+            object_origins[item] = module
+
+    class module(ModuleType):
+
+        def __getattr__(self, name):
+            if name in object_origins:
+                module = __import__(object_origins[name], None, None, [name])
+                for extra_name in all_by_module[module.__name__]:
+                    setattr(self, extra_name, getattr(module, extra_name))
+                return getattr(module, name)
+            return ModuleType.__getattribute__(self, name)
+
+        def __dir__(self):
+            result = list(new_module.__all__)
+            result.extend(("__file__", "__path__", "__doc__", "__all__",
+                           "__docformat__", "__name__", "__path__", "VERSION",
+                           "__package__", "__version__", "__author__",
+                           "__contact__", "__homepage__", "__docformat__"))
+            return result
+
+    # keep a reference to this module so that it's not garbage collected
+    old_module = sys.modules[__name__]
+
+    new_module = sys.modules[__name__] = module(__name__)
+    new_module.__dict__.update({
+        "__file__": __file__,
+        "__path__": __path__,
+        "__doc__": __doc__,
+        "__all__": tuple(object_origins),
+        "__version__": __version__,
+        "__author__": __author__,
+        "__contact__": __contact__,
+        "__homepage__": __homepage__,
+        "__docformat__": __docformat__,
+        "VERSION": VERSION})