Changed Component.__init__ so that config is not deepcopy'd.

Previously, we were deepcoping the config for each component.  This 
causes overhead and it is not clear at this point that having components
share config (by reference) is a bad idea.

IPython/core/component.py

@@ -1,317 +1,325 b''
 #!/usr/bin/env python
 # encoding: utf-8
 """
 A lightweight component system for IPython.
 
 Authors:
 
 * Brian Granger
 * Fernando Perez
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2009  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from copy import deepcopy
 import datetime
 from weakref import WeakValueDictionary
 
 from IPython.utils.importstring import import_item
 from IPython.config.loader import Config
 from IPython.utils.traitlets import (
     HasTraitlets, TraitletError, MetaHasTraitlets, Instance, This
 )
 
 
 #-----------------------------------------------------------------------------
 # Helper classes for Components
 #-----------------------------------------------------------------------------
 
 
 class ComponentError(Exception):
     pass
 
 class MetaComponentTracker(type):
     """A metaclass that tracks instances of Components and its subclasses."""
 
     def __init__(cls, name, bases, d):
         super(MetaComponentTracker, cls).__init__(name, bases, d)
         cls.__instance_refs = WeakValueDictionary()
         cls.__numcreated = 0
 
     def __call__(cls, *args, **kw):
         """Called when a class is called (instantiated)!!!
         
         When a Component or subclass is instantiated, this is called and
         the instance is saved in a WeakValueDictionary for tracking.
         """
         instance = cls.__new__(cls, *args, **kw)
 
         # Register the instance before __init__ is called so get_instances 
         # works inside __init__ methods!
         indices = cls.register_instance(instance)
 
         # This is in a try/except because of the __init__ method fails, the
         # instance is discarded and shouldn't be tracked.
         try:
             if isinstance(instance, cls):
                 cls.__init__(instance, *args, **kw)
         except:
             # Unregister the instance because __init__ failed!
             cls.unregister_instances(indices)
             raise
         else:
             return instance
 
     def register_instance(cls, instance):
         """Register instance with cls and its subclasses."""
         # indices is a list of the keys used to register the instance
         # with.  This list is needed if the instance needs to be unregistered.
         indices = []
         for c in cls.__mro__:
             if issubclass(cls, c) and issubclass(c, Component):
                 c.__numcreated += 1
                 indices.append(c.__numcreated)
                 c.__instance_refs[c.__numcreated] = instance
             else:
                 break
         return indices
 
     def unregister_instances(cls, indices):
         """Unregister instance with cls and its subclasses."""
         for c, index in zip(cls.__mro__, indices):
             try:
                 del c.__instance_refs[index]
             except KeyError:
                 pass
 
     def clear_instances(cls):
         """Clear all instances tracked by cls."""
         cls.__instance_refs.clear()
         cls.__numcreated = 0
 
     def get_instances(cls, name=None, root=None, klass=None):
         """Get all instances of cls and its subclasses.
 
         Parameters
         ----------
         name : str
             Limit to components with this name.
         root : Component or subclass
             Limit to components having this root.
         klass : class or str
             Limits to instances of the class or its subclasses.  If a str
             is given ut must be in the form 'foo.bar.MyClass'.  The str
             form of this argument is useful for forward declarations.
         """
         if klass is not None:
             if isinstance(klass, basestring):
                 klass = import_item(klass)
             # Limit search to instances of klass for performance
             if issubclass(klass, Component):
                 return klass.get_instances(name=name, root=root)
         instances = cls.__instance_refs.values()
         if name is not None:
             instances = [i for i in instances if i.name == name]
         if klass is not None:
             instances = [i for i in instances if isinstance(i, klass)]
         if root is not None:
             instances = [i for i in instances if i.root == root]
         return instances
 
     def get_instances_by_condition(cls, call, name=None, root=None,
                                    klass=None):
         """Get all instances of cls, i such that call(i)==True.
 
         This also takes the ``name`` and ``root`` and ``classname`` 
         arguments of :meth:`get_instance`
         """
         return [i for i in cls.get_instances(name, root, klass) if call(i)]
 
 
 def masquerade_as(instance, cls):
     """Let instance masquerade as an instance of cls.
 
     Sometimes, such as in testing code, it is useful to let a class
     masquerade as another.  Python, being duck typed, allows this by 
     default.  But, instances of components are tracked by their class type.
 
     After calling this, cls.get_instances() will return ``instance``.  This
     does not, however, cause isinstance(instance, cls) to return ``True``.
 
     Parameters
     ----------
     instance : an instance of a Component or Component subclass
         The instance that will pretend to be a cls.
     cls : subclass of Component
         The Component subclass that instance will pretend to be.
     """
     cls.register_instance(instance)
 
 
 class ComponentNameGenerator(object):
     """A Singleton to generate unique component names."""
 
     def __init__(self, prefix):
         self.prefix = prefix
         self.i = 0
 
     def __call__(self):
         count = self.i
         self.i += 1
         return "%s%s" % (self.prefix, count)
 
 
 ComponentNameGenerator = ComponentNameGenerator('ipython.component')
 
 
 class MetaComponent(MetaHasTraitlets, MetaComponentTracker):
     pass
 
 
 #-----------------------------------------------------------------------------
 # Component implementation
 #-----------------------------------------------------------------------------
 
 
 class Component(HasTraitlets):
 
     __metaclass__ = MetaComponent
 
     # Traitlets are fun!
     config = Instance(Config,(),{})
     parent = This()
     root = This()
     created = None
 
     def __init__(self, parent, name=None, config=None):
         """Create a component given a parent and possibly and name and config.
 
         Parameters
         ----------
         parent : Component subclass
             The parent in the component graph.  The parent is used
             to get the root of the component graph.
         name : str
             The unique name of the component.  If empty, then a unique
             one will be autogenerated.
         config : Config
             If this is empty, self.config = parent.config, otherwise
             self.config = config and root.config is ignored.  This argument
             should only be used to *override* the automatic inheritance of 
             parent.config.  If a caller wants to modify parent.config 
             (not override), the caller should make a copy and change 
             attributes and then pass the copy to this argument.
         
         Notes
         -----
         Subclasses of Component must call the :meth:`__init__` method of
         :class:`Component` *before* doing anything else and using 
         :func:`super`::
         
             class MyComponent(Component):
                 def __init__(self, parent, name=None, config=None):
                     super(MyComponent, self).__init__(parent, name, config)
                     # Then any other code you need to finish initialization.
 
         This ensures that the :attr:`parent`, :attr:`name` and :attr:`config`
         attributes are handled properly.
         """
         super(Component, self).__init__()
         self._children = []
         if name is None:
             self.name = ComponentNameGenerator()
         else:
             self.name = name
         self.root = self # This is the default, it is set when parent is set
         self.parent = parent
         if config is not None:
-            self.config = deepcopy(config)
+            self.config = config
+            # We used to deepcopy, but for now we are trying to just save
+            # by reference.  This *could* have side effects as all components
+            # will share config.
+            # self.config = deepcopy(config)
         else:
             if self.parent is not None:
-                self.config = deepcopy(self.parent.config)
+                self.config = self.parent.config
+                # We used to deepcopy, but for now we are trying to just save
+                # by reference.  This *could* have side effects as all components
+                # will share config.
+                # self.config = deepcopy(self.parent.config)
 
         self.created = datetime.datetime.now()
 
     #-------------------------------------------------------------------------
     # Static traitlet notifiations
     #-------------------------------------------------------------------------
 
     def _parent_changed(self, name, old, new):
         if old is not None:
             old._remove_child(self)
         if new is not None:
             new._add_child(self)
 
         if new is None:
             self.root = self
         else:
             self.root = new.root
 
     def _root_changed(self, name, old, new):
         if self.parent is None:
             if not (new is self):
                 raise ComponentError("Root not self, but parent is None.")
         else:
             if not self.parent.root is new:
                 raise ComponentError("Error in setting the root attribute: "
                                      "root != parent.root")
 
     def _config_changed(self, name, old, new):
         """Update all the class traits having ``config=True`` as metadata.
 
         For any class traitlet with a ``config`` metadata attribute that is
         ``True``, we update the traitlet with the value of the corresponding
         config entry.
         """
         # Get all traitlets with a config metadata entry that is True
         traitlets = self.traitlets(config=True)
 
         # We auto-load config section for this class as well as any parent
         # classes that are Component subclasses.  This starts with Component
         # and works down the mro loading the config for each section.
         section_names = [cls.__name__ for cls in \
             reversed(self.__class__.__mro__) if 
             issubclass(cls, Component) and issubclass(self.__class__, cls)]
 
         for sname in section_names:
             # Don't do a blind getattr as that would cause the config to 
             # dynamically create the section with name self.__class__.__name__.
             if new._has_section(sname):
                 my_config = new[sname]
                 for k, v in traitlets.items():
                     try:
                         config_value = my_config[k]
                     except KeyError:
                         pass
                     else:
                         # print "Setting %s.%s from %s.%s=%r" % \
                         #     (self.__class__.__name__,k,sname,k,config_value)
                         setattr(self, k, config_value)
 
     @property
     def children(self):
         """A list of all my child components."""
         return self._children
 
     def _remove_child(self, child):
         """A private method for removing children components."""
         if child in self._children:
             index = self._children.index(child)
             del self._children[index]
 
     def _add_child(self, child):
         """A private method for adding children components."""
         if child not in self._children:
             self._children.append(child)
 
     def __repr__(self):
         return "<%s('%s')>" % (self.__class__.__name__, self.name)

IPython/core/tests/test_component.py

@@ -1,214 +1,214 b''
 #!/usr/bin/env python
 # encoding: utf-8
 """
 Tests for IPython.core.component
 
 Authors:
 
 * Brian Granger
 * Fernando Perez (design help)
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2009  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from unittest import TestCase
 
 from IPython.core.component import Component, ComponentError
 from IPython.utils.traitlets import (
     TraitletError, Int, Float, Str
 )
 from IPython.config.loader import Config
 
 
 #-----------------------------------------------------------------------------
 # Test cases
 #-----------------------------------------------------------------------------
 
 
 class TestComponentMeta(TestCase):
 
     def test_get_instances(self):
         class BaseComponent(Component):
             pass
         c1 = BaseComponent(None)
         c2 = BaseComponent(c1)
         self.assertEquals(BaseComponent.get_instances(),[c1,c2])
 
     def test_get_instances_subclass(self):
         class MyComponent(Component):
             pass
         class MyOtherComponent(MyComponent):
             pass
         c1 = MyComponent(None)
         c2 = MyOtherComponent(c1)
         c3 = MyOtherComponent(c2)
         self.assertEquals(MyComponent.get_instances(), [c1, c2, c3])
         self.assertEquals(MyOtherComponent.get_instances(), [c2, c3])
 
     def test_get_instances_root(self):
         class MyComponent(Component):
             pass
         class MyOtherComponent(MyComponent):
             pass
         c1 = MyComponent(None)
         c2 = MyOtherComponent(c1)
         c3 = MyOtherComponent(c2)
         c4 = MyComponent(None)
         c5 = MyComponent(c4)
         self.assertEquals(MyComponent.get_instances(root=c1), [c1, c2, c3])
         self.assertEquals(MyComponent.get_instances(root=c4), [c4, c5])
 
 
 class TestComponent(TestCase):
 
     def test_parent_child(self):
         c1 = Component(None)
         c2 = Component(c1)
         c3 = Component(c1)
         c4 = Component(c3)
         self.assertEquals(c1.parent, None)
         self.assertEquals(c2.parent, c1)
         self.assertEquals(c3.parent, c1)
         self.assertEquals(c4.parent, c3)
         self.assertEquals(c1.children, [c2, c3])
         self.assertEquals(c2.children, [])
         self.assertEquals(c3.children, [c4])
         self.assertEquals(c4.children, [])
 
     def test_root(self):
         c1 = Component(None)
         c2 = Component(c1)
         c3 = Component(c1)
         c4 = Component(c3)
         self.assertEquals(c1.root, c1.root)
         self.assertEquals(c2.root, c1)
         self.assertEquals(c3.root, c1)
         self.assertEquals(c4.root, c1)
 
     def test_change_parent(self):
         c1 = Component(None)
         c2 = Component(None)
         c3 = Component(c1)
         self.assertEquals(c3.root, c1)
         self.assertEquals(c3.parent, c1)
         self.assertEquals(c1.children,[c3])
         c3.parent = c2
         self.assertEquals(c3.root, c2)
         self.assertEquals(c3.parent, c2)
         self.assertEquals(c2.children,[c3])
         self.assertEquals(c1.children,[])
 
     def test_subclass_parent(self):
         c1 = Component(None)
         self.assertRaises(TraitletError, setattr, c1, 'parent', 10)
 
         class MyComponent(Component):
             pass
         c1 = Component(None)
         c2 = MyComponent(c1)
         self.assertEquals(MyComponent.parent.this_class, Component)
         self.assertEquals(c2.parent, c1)
 
     def test_bad_root(self):
         c1 = Component(None)
         c2 = Component(None)
         c3 = Component(None)
         self.assertRaises(ComponentError, setattr, c1, 'root', c2)
         c1.parent = c2
         self.assertEquals(c1.root, c2)
         self.assertRaises(ComponentError, setattr, c1, 'root', c3)
 
 
 class TestComponentConfig(TestCase):
 
     def test_default(self):
         c1 = Component(None)
         c2 = Component(c1)
         c3 = Component(c2)
         self.assertEquals(c1.config, c2.config)
         self.assertEquals(c2.config, c3.config)
 
     def test_custom(self):
         config = Config()
         config.foo = 'foo'
         config.bar = 'bar'
         c1 = Component(None, config=config)
         c2 = Component(c1)
         c3 = Component(c2)
         self.assertEquals(c1.config, config)
         self.assertEquals(c2.config, config)
         self.assertEquals(c3.config, config)
-        # Test that we always make copies
-        self.assert_(c1.config is not config)
-        self.assert_(c2.config is not config)
-        self.assert_(c3.config is not config)
-        self.assert_(c1.config is not c2.config)
-        self.assert_(c2.config is not c3.config)
+        # Test that copies are not made
+        self.assert_(c1.config is config)
+        self.assert_(c2.config is config)
+        self.assert_(c3.config is config)
+        self.assert_(c1.config is c2.config)
+        self.assert_(c2.config is c3.config)
         
     def test_inheritance(self):
         class MyComponent(Component):
             a = Int(1, config=True)
             b = Float(1.0, config=True)
             c = Str('no config')
         config = Config()
         config.MyComponent.a = 2
         config.MyComponent.b = 2.0
         c1 = MyComponent(None, config=config)
         c2 = MyComponent(c1)
         self.assertEquals(c1.a, config.MyComponent.a)
         self.assertEquals(c1.b, config.MyComponent.b)
         self.assertEquals(c2.a, config.MyComponent.a)
         self.assertEquals(c2.b, config.MyComponent.b)
         c4 = MyComponent(c2, config=Config())
         self.assertEquals(c4.a, 1)
         self.assertEquals(c4.b, 1.0)
 
     def test_parent(self):
         class Foo(Component):
             a = Int(0, config=True)
             b = Str('nope', config=True)
         class Bar(Foo):
             b = Str('gotit', config=False)
             c = Float(config=True)
         config = Config()
         config.Foo.a = 10
         config.Foo.b = "wow"
         config.Bar.b = 'later'
         config.Bar.c = 100.0
         f = Foo(None, config=config)
         b = Bar(f)
         self.assertEquals(f.a, 10)
         self.assertEquals(f.b, 'wow')
         self.assertEquals(b.b, 'gotit')
         self.assertEquals(b.c, 100.0)
 
 
 class TestComponentName(TestCase):
 
     def test_default(self):
         class MyComponent(Component):
             pass
         c1 = Component(None)
         c2 = MyComponent(None)
         c3 = Component(c2)
         self.assertNotEquals(c1.name, c2.name)
         self.assertNotEquals(c1.name, c3.name)
 
     def test_manual(self):
         class MyComponent(Component):
             pass
         c1 = Component(None, name='foo')
         c2 = MyComponent(None, name='bar')
         c3 = Component(c2, name='bah')
         self.assertEquals(c1.name, 'foo')
         self.assertEquals(c2.name, 'bar')
         self.assertEquals(c3.name, 'bah')