Task methods can't use old-style base class, also fix __call__ and .apply() for task methods

celery/app/task.py

@@ -320,6 +320,9 @@ class Task(object):
         _task_stack.push(self)
         self.push_request()
         try:
+            # add self if this is a bound task
+            if self.__self__ is not None:
+                return self.run(self.__self__, *args, **kwargs)
             return self.run(*args, **kwargs)
         finally:
             self.pop_request()
@@ -582,7 +585,10 @@ class Task(object):
         from celery.task.trace import eager_trace_task
 
         app = self._get_app()
-        args = args or []
+        args = args or ()
+        # add 'self' if this is a bound method.
+        if self.__self__ is not None:
+            args = (self.__self__, ) + tuple(args)
         kwargs = kwargs or {}
         task_id = options.get('task_id') or uuid()
         retries = options.get('retries', 0)

celery/contrib/methods.py

@@ -30,6 +30,33 @@ or with any task decorator:
         def add(self, x, y):
             return x + y
 
+.. note::
+
+    The task must use the new Task base class (:class:`celery.Task`),
+    and the old base class using classmethods (``celery.task.Task``,
+    ``celery.task.base.Task``).
+
+    This means that you have to use the task decorator from a Celery app
+    instance, and not the old-API:
+
+    .. code-block:: python
+
+
+        from celery import task       # BAD
+        from celery.task import task  # ALSO BAD
+
+        # GOOD:
+        celery = Celery(...)
+
+        @celery.task(filter=task_method)
+        def foo(self): pass
+
+        # ALSO GOOD:
+        from celery import current_app
+
+        @current_app.task(filter=task_method)
+        def foo(self): pass
+
 Caveats
 -------
 
@@ -73,7 +100,7 @@ from __future__ import absolute_import
 
 from functools import partial
 
-from celery import task as _task
+from celery import current_app
 
 
 class task_method(object):
@@ -89,4 +116,5 @@ class task_method(object):
         return task
 
 
-task = partial(_task, filter=task_method)
+def task(*args, **kwargs):
+    return current_app.task(*args, **dict(kwargs, filter=task_method))