First take at cleaning up extensions.

IPython/extensions/__init__.py

@@ -1,13 +1,2 b''
 # -*- coding: utf-8 -*-
-"""This directory is meant for special-purpose extensions to IPython.
-
-This can include things which alter the syntax processing stage (see
-PhysicalQ_Input for an example of how to do this).
-
-Any file located here can be called with an 'execfile =' option as
-
-  execfile = extensions/filename.py
-
-since the IPython directory itself is already part of the search path for
-files listed as 'execfile ='.
-"""
+"""This directory is meant for IPython extensions."""

IPython/extensions/parallelmagic.py

@@ -16,8 +16,8 b''
 
 import new
 
-from IPython.core.component import Component
-from IPython.utils.traitlets import Bool, Any
+from IPython.config.configurable import Configurable
+from IPython.utils.traitlets import Bool, Any, Instance
 from IPython.utils.autoattr import auto_attr
 from IPython.testing import decorators as testdec
 
@@ -31,28 +31,20 b' Use activate() on a MultiEngineClient object to activate it for magics.'
 """
 
 
-class ParalleMagicComponent(Component):
+class ParalleMagicComponent(Configurable):
     """A component to manage the %result, %px and %autopx magics."""
 
     active_multiengine_client = Any()
     verbose = Bool(False, config=True)
+    shell = Instance('IPython.core.iplib.InteractiveShell')
 
-    def __init__(self, parent, name=None, config=None):
-        super(ParalleMagicComponent, self).__init__(parent, name=name, config=config)
+    def __init__(self, shell, config=None):
+        super(ParalleMagicComponent, self).__init__(config=config)
+        self.shell = shell
         self._define_magics()
         # A flag showing if autopx is activated or not
         self.autopx = False
 
-    # Access other components like this rather than by a regular attribute.
-    # This won't lookup the InteractiveShell object until it is used and
-    # then it is cached.  This is both efficient and couples this class 
-    # more loosely to InteractiveShell.
-    @auto_attr
-    def shell(self):
-        return Component.get_instances(
-            root=self.root,
-            klass='IPython.core.iplib.InteractiveShell')[0]
-
     def _define_magics(self):
         """Define the magic functions."""
         self.shell.define_magic('result', self.magic_result)
@@ -204,6 +196,6 b' def load_ipython_extension(ip):'
     """Load the extension in IPython."""
     global _loaded
     if not _loaded:
-        prd = ParalleMagicComponent(ip, name='parallel_magic')
+        prd = ParalleMagicComponent(ip, config=ip.config)
         _loaded = True
 

IPython/extensions/pretty.py

@@ -37,8 +37,8 b' by doing::'
 
 from IPython.core.error import TryNext
 from IPython.external import pretty
-from IPython.core.component import Component
-from IPython.utils.traitlets import Bool, List
+from IPython.config.configurable import Configurable
+from IPython.utils.traitlets import Bool, List, Instance
 from IPython.utils.io import Term
 from IPython.utils.autoattr import auto_attr
 from IPython.utils.importstring import import_item
@@ -51,10 +51,11 b' from IPython.utils.importstring import import_item'
 _loaded = False
 
 
-class PrettyResultDisplay(Component):
+class PrettyResultDisplay(Configurable):
     """A component for pretty printing on steroids."""
 
     verbose = Bool(False, config=True)
+    shell = Instance('IPython.core.iplib.InteractiveShell')
 
     # A list of (type, func_name), like
     # [(dict, 'my_dict_printer')]
@@ -66,8 +67,9 b' class PrettyResultDisplay(Component):'
     # The final argument can also be a callable
     defaults_for_type_by_name = List(default_value=[], config=True)
 
-    def __init__(self, parent, name=None, config=None):
-        super(PrettyResultDisplay, self).__init__(parent, name=name, config=config)
+    def __init__(self, shell, config=None):
+        super(PrettyResultDisplay, self).__init__(config=config)
+        self.shell = shell
         self._setup_defaults()
 
     def _setup_defaults(self):
@@ -87,16 +89,6 b' class PrettyResultDisplay(Component):'
         else:
             raise TypeError('func_name must be a str or callable, got: %r' % func_name)
 
-    # Access other components like this rather than by a regular attribute.
-    # This won't lookup the InteractiveShell object until it is used and
-    # then it is cached.  This is both efficient and couples this class 
-    # more loosely to InteractiveShell.
-    @auto_attr
-    def shell(self):
-        return Component.get_instances(
-            root=self.root,
-            klass='IPython.core.iplib.InteractiveShell')[0]
-
     def __call__(self, otherself, arg):
         """Uber-pretty-printing display hook.
 
@@ -132,7 +124,7 b' def load_ipython_extension(ip):'
     """Load the extension in IPython as a hook."""
     global _loaded
     if not _loaded:
-        prd = PrettyResultDisplay(ip, name='pretty_result_display')
+        prd = PrettyResultDisplay(ip, config=ip.config)
         ip.set_hook('result_display', prd, priority=99)
         _loaded = True
         return prd