diff --git a/IPython/core/component.py b/IPython/core/component.py
index e8f7e92..d86e60f 100644
--- a/IPython/core/component.py
+++ b/IPython/core/component.py
@@ -34,6 +34,9 @@ from IPython.utils.traitlets import (
#-----------------------------------------------------------------------------
+class ComponentError(Exception):
+ pass
+
class MetaComponentTracker(type):
"""A metaclass that tracks instances of Components and its subclasses."""
@@ -116,12 +119,12 @@ class Component(HasTraitlets):
__metaclass__ = MetaComponent
# Traitlets are fun!
- config = Instance(Struct)
- parent = This(allow_none=True)
- root = This(allow_none=True)
+ config = Instance(Struct,(),{})
+ parent = This()
+ root = This()
def __init__(self, parent, name=None, config=None):
- """Create a component given a parent.
+ """Create a component given a parent and possibly and name and config.
Parameters
----------
@@ -132,13 +135,26 @@ class Component(HasTraitlets):
The unique name of the component. If empty, then a unique
one will be autogenerated.
config : Config
- If this is empty, self.config = root.config, otherwise
- self.config = config and root.config is ignored. This argument
- should be used to pass the config to the root. Otherwise, it
- can be used to *override* the inheritance of root.config. If a
- caller wants to modify root.config (not override), the caller
- should make a copy and change attributes and then pass the copy
- to this argument. We might think about changing this behavior.
+ 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 = []
@@ -169,6 +185,15 @@ class Component(HasTraitlets):
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")
+
@property
def children(self):
"""A list of all my child components."""
diff --git a/IPython/core/tests/test_component.py b/IPython/core/tests/test_component.py
index e1bafa2..ebcb61a 100644
--- a/IPython/core/tests/test_component.py
+++ b/IPython/core/tests/test_component.py
@@ -22,7 +22,11 @@ Authors:
from unittest import TestCase
-from IPython.core.component import Component
+from IPython.core.component import Component, ComponentError
+from IPython.utils.traitlets import (
+ TraitletError
+)
+from IPython.utils.ipstruct import Struct
#-----------------------------------------------------------------------------
@@ -39,6 +43,30 @@ class TestComponentMeta(TestCase):
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(MyComponent.get_instances(klass=MyOtherComponent), [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):
@@ -65,3 +93,78 @@ class TestComponent(TestCase):
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 = Struct()
+ 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)
+
+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')
diff --git a/IPython/utils/tests/test_traitlets.py b/IPython/utils/tests/test_traitlets.py
index ce1f76d..d51f5ee 100644
--- a/IPython/utils/tests/test_traitlets.py
+++ b/IPython/utils/tests/test_traitlets.py
@@ -164,6 +164,17 @@ class TestHasTraitletsMeta(TestCase):
c.c = 10
self.assertEquals(c.c,10)
+ def test_this_class(self):
+ class A(HasTraitlets):
+ t = This()
+ tt = This()
+ class B(A):
+ tt = This()
+ ttt = This()
+ self.assertEquals(A.t.this_class, A)
+ self.assertEquals(B.t.this_class, A)
+ self.assertEquals(B.tt.this_class, B)
+ self.assertEquals(B.ttt.this_class, B)
class TestHasTraitletsNotify(TestCase):
@@ -323,7 +334,7 @@ class TestTraitletKeys(TestCase):
a = Int
b = Float
a = A()
- self.assertEquals(a.traitlet_keys(),['a','b'])
+ self.assertEquals(a.traitlet_names(),['a','b'])
#-----------------------------------------------------------------------------
@@ -484,6 +495,28 @@ class TestThis(TestCase):
f.this = Foo()
self.assert_(isinstance(f.this, Foo))
+ def test_subclass(self):
+ class Foo(HasTraitlets):
+ t = This()
+ class Bar(Foo):
+ pass
+ f = Foo()
+ b = Bar()
+ f.t = b
+ b.t = f
+ self.assertEquals(f.t, b)
+ self.assertEquals(b.t, f)
+
+ def test_subclass_override(self):
+ class Foo(HasTraitlets):
+ t = This()
+ class Bar(Foo):
+ t = This()
+ f = Foo()
+ b = Bar()
+ f.t = b
+ self.assertEquals(f.t, b)
+ self.assertRaises(TraitletError, setattr, b, 't', f)
class TraitletTestBase(TestCase):
"""A best testing class for basic traitlet types."""
diff --git a/IPython/utils/traitlets.py b/IPython/utils/traitlets.py
index cd30fe3..f83ea9f 100644
--- a/IPython/utils/traitlets.py
+++ b/IPython/utils/traitlets.py
@@ -139,6 +139,23 @@ def parse_notifier_name(name):
class TraitletType(object):
+ """A base class for all traitlet descriptors.
+
+ Notes
+ -----
+ Our implementation of traitlets is based on Python's descriptor
+ prototol. This class is the base class for all such descriptors. The
+ only magic we use is a custom metaclass for the main :class:`HasTraitlets`
+ class that does the following:
+
+ 1. Sets the :attr:`name` attribute of every :class:`TraitletType`
+ instance in the class dict to the name of the attribute.
+ 2. Sets the :attr:`this_class` attribute of every :class:`TraitletType`
+ instance in the class dict to the *class* that declared the traitlet.
+ This is used by the :class:`This` traitlet to allow subclasses to
+ accept superclasses for :class:`This` values.
+ """
+
metadata = {}
default_value = Undefined
@@ -235,6 +252,17 @@ class MetaHasTraitlets(type):
"""
def __new__(mcls, name, bases, classdict):
+ """Create the HasTraitlets class.
+
+ This instantiates all TraitletTypes in the class dict and sets their
+ :attr:`name` attribute.
+ """
+ # print "========================="
+ # print "MetaHasTraitlets.__new__"
+ # print "mcls, ", mcls
+ # print "name, ", name
+ # print "bases, ", bases
+ # print "classdict, ", classdict
for k,v in classdict.iteritems():
if isinstance(v, TraitletType):
v.name = k
@@ -245,6 +273,22 @@ class MetaHasTraitlets(type):
classdict[k] = vinst
return super(MetaHasTraitlets, mcls).__new__(mcls, name, bases, classdict)
+ def __init__(cls, name, bases, classdict):
+ """Finish initializing the HasTraitlets class.
+
+ This sets the :attr:`this_class` attribute of each TraitletType in the
+ class dict to the newly created class ``cls``.
+ """
+ # print "========================="
+ # print "MetaHasTraitlets.__init__"
+ # print "cls, ", cls
+ # print "name, ", name
+ # print "bases, ", bases
+ # print "classdict, ", classdict
+ for k, v in classdict.iteritems():
+ if isinstance(v, TraitletType):
+ v.this_class = cls
+ super(MetaHasTraitlets, cls).__init__(name, bases, classdict)
class HasTraitlets(object):
@@ -364,7 +408,7 @@ class HasTraitlets(object):
for n in names:
self._add_notifiers(handler, n)
- def traitlet_keys(self):
+ def traitlet_names(self):
"""Get a list of all the names of this classes traitlets."""
return [memb[0] for memb in inspect.getmembers(self.__class__) if isinstance(memb[1], TraitletType)]
@@ -566,7 +610,10 @@ class This(ClassBasedTraitletType):
super(This, self).__init__(None, **metadata)
def validate(self, obj, value):
- if isinstance(value, obj.__class__) or (value is None):
+ # What if value is a superclass of obj.__class__? This is
+ # complicated if it was the superclass that defined the This
+ # traitlet.
+ if isinstance(value, self.this_class) or (value is None):
return value
else:
self.error(obj, value)