Merge pull request #5353 from Zaharid/nonetraits

Allow None for most traits

IPython/utils/tests/test_traitlets.py

@@ -673,6 +673,23 b' class TraitTestBase(TestCase):'
         if hasattr(self, '_default_value'):
             self.assertEqual(self._default_value, self.obj.value)
 
+    def test_allow_none(self):
+        if (hasattr(self, '_bad_values') and hasattr(self, '_good_values') and
+        None in self._bad_values):
+            trait=self.obj.traits()['value']
+            try:
+                trait.allow_none = True
+                self._bad_values.remove(None)
+                #skip coerce. Allow None casts None to None.
+                self.assign(None)
+                self.assertEqual(self.obj.value,None)
+                self.test_good_values()
+                self.test_bad_values()
+            finally:
+                #tear down
+                trait.allow_none = False
+                self._bad_values.append(None)
+
     def tearDown(self):
         # restore default value after tests, if set
         if hasattr(self, '_default_value'):
@@ -830,7 +847,7 b' class TestObjectName(TraitTestBase):'
     _default_value = "abc"
     _good_values = ["a", "gh", "g9", "g_", "_G", u"a345_"]
     _bad_values = [1, "", u"€", "9g", "!", "#abc", "aj@", "a.b", "a()", "a[0]",
-                                                            object(), object]
+                                                        None, object(), object]
     if sys.version_info[0] < 3:
         _bad_values.append(u"þ")
     else:
@@ -845,7 +862,7 b' class TestDottedObjectName(TraitTestBase):'
 
     _default_value = "a.b"
     _good_values = ["A", "y.t", "y765.__repr__", "os.path.join", u"os.path.join"]
-    _bad_values = [1, u"abc.€", "_.@", ".", ".abc", "abc.", ".abc."]
+    _bad_values = [1, u"abc.€", "_.@", ".", ".abc", "abc.", ".abc.", None]
     if sys.version_info[0] < 3:
         _bad_values.append(u"t.þ")
     else:
@@ -862,7 +879,7 b' class TestTCPAddress(TraitTestBase):'
 
     _default_value = ('127.0.0.1',0)
     _good_values = [('localhost',0),('192.168.0.1',1000),('www.google.com',80)]
-    _bad_values = [(0,0),('localhost',10.0),('localhost',-1)]
+    _bad_values = [(0,0),('localhost',10.0),('localhost',-1), None]
 
 class ListTrait(HasTraits):
 
@@ -919,14 +936,14 b' class TestLenList(TraitTestBase):'
 
 class TupleTrait(HasTraits):
 
-    value = Tuple(Int)
+    value = Tuple(Int(allow_none=True))
 
 class TestTupleTrait(TraitTestBase):
 
     obj = TupleTrait()
 
     _default_value = None
-    _good_values = [(1,), None, (0,), [1]]
+    _good_values = [(1,), None, (0,), [1], (None,)]
     _bad_values = [10, (1,2), ('a'), ()]
 
     def coerce(self, value):

IPython/utils/traitlets.py

@@ -252,13 +252,16 b' class TraitType(object):'
 
     metadata = {}
     default_value = Undefined
+    allow_none = False
     info_text = 'any value'
 
-    def __init__(self, default_value=NoDefaultSpecified, **metadata):
+    def __init__(self, default_value=NoDefaultSpecified, allow_none=None, **metadata):
         """Create a TraitType.
         """
         if default_value is not NoDefaultSpecified:
             self.default_value = default_value
+        if allow_none is not None:
+            self.allow_none = allow_none
 
         if len(metadata) > 0:
             if len(self.metadata) > 0:
@@ -371,6 +374,8 b' class TraitType(object):'
             obj._notify_trait(self.name, old_value, new_value)
 
     def _validate(self, obj, value):
+        if value is None and self.allow_none:
+            return value
         if hasattr(self, 'validate'):
             return self.validate(obj, value)
         elif hasattr(self, 'is_valid_for'):
@@ -745,9 +750,8 b' class Type(ClassBasedTraitType):'
             raise TraitError("A Type trait must specify a class.")
 
         self.klass       = klass
-        self._allow_none = allow_none
 
-        super(Type, self).__init__(default_value, **metadata)
+        super(Type, self).__init__(default_value, allow_none=allow_none, **metadata)
 
     def validate(self, obj, value):
         """Validates that the value is a valid object instance."""
@@ -755,8 +759,7 b' class Type(ClassBasedTraitType):'
             if issubclass(value, self.klass):
                 return value
         except:
-            if (value is None) and (self._allow_none):
-                return value
+            pass
 
         self.error(obj, value)
 
@@ -767,7 +770,7 b' class Type(ClassBasedTraitType):'
         else:
             klass = self.klass.__name__
         result = 'a subclass of ' + klass
-        if self._allow_none:
+        if self.allow_none:
             return result + ' or None'
         return result
 
@@ -831,8 +834,6 b' class Instance(ClassBasedTraitType):'
         not (but not both), None is replace by ``()`` or ``{}``.
         """
 
-        self._allow_none = allow_none
-
         if (klass is None) or (not (inspect.isclass(klass) or isinstance(klass, py3compat.string_types))):
             raise TraitError('The klass argument must be a class'
                                 ' you gave: %r' % klass)
@@ -856,14 +857,9 b' class Instance(ClassBasedTraitType):'
 
             default_value = DefaultValueGenerator(*args, **kw)
 
-        super(Instance, self).__init__(default_value, **metadata)
+        super(Instance, self).__init__(default_value, allow_none=allow_none, **metadata)
 
     def validate(self, obj, value):
-        if value is None:
-            if self._allow_none:
-                return value
-            self.error(obj, value)
-
         if isinstance(value, self.klass):
             return value
         else:
@@ -875,7 +871,7 b' class Instance(ClassBasedTraitType):'
         else:
             klass = self.klass.__name__
         result = class_of(klass)
-        if self._allow_none:
+        if self.allow_none:
             return result + ' or None'
 
         return result
@@ -1169,14 +1165,9 b' class Enum(TraitType):'
 
     def __init__(self, values, default_value=None, allow_none=True, **metadata):
         self.values = values
-        self._allow_none = allow_none
-        super(Enum, self).__init__(default_value, **metadata)
+        super(Enum, self).__init__(default_value, allow_none=allow_none, **metadata)
 
     def validate(self, obj, value):
-        if value is None:
-            if self._allow_none:
-                return value
-
         if value in self.values:
                 return value
         self.error(obj, value)
@@ -1184,7 +1175,7 b' class Enum(TraitType):'
     def info(self):
         """ Returns a description of the trait."""
         result = 'any of ' + repr(self.values)
-        if self._allow_none:
+        if self.allow_none:
             return result + ' or None'
         return result
 
@@ -1192,10 +1183,6 b' class CaselessStrEnum(Enum):'
     """An enum of strings that are caseless in validate."""
 
     def validate(self, obj, value):
-        if value is None:
-            if self._allow_none:
-                return value
-
         if not isinstance(value, py3compat.string_types):
             self.error(obj, value)
 
@@ -1290,7 +1277,7 b' class Container(Instance):'
             return value
         for v in value:
             try:
-                v = self._trait.validate(obj, v)
+                v = self._trait._validate(obj, v)
             except TraitError:
                 self.element_error(obj, v, self._trait)
             else:
@@ -1366,8 +1353,6 b' class List(Container):'
     
     def validate(self, obj, value):
         value = super(List, self).validate(obj, value)
-        if value is None:
-            return value
 
         value = self.validate_elements(obj, value)
 
@@ -1463,7 +1448,7 b' class Tuple(Container):'
         validated = []
         for t,v in zip(self._traits, value):
             try:
-                v = t.validate(obj, v)
+                v = t._validate(obj, v)
             except TraitError:
                 self.element_error(obj, v, t)
             else: