From b4c913192842f5e6610f8177e88041edd1a93fd6 Mon Sep 17 00:00:00 2001
From: Ryan Morshead <ryan.morshead@gmail.com>
Date: Fri, 1 Jul 2016 09:37:45 -0700
Subject: [PATCH] misc and tests for validate and default via tags

---
 traitlets/tests/test_traitlets.py | 52 ++++++++++++++++++++++++++++-
 traitlets/traitlets.py            | 54 ++++++++++++++++++-------------
 2 files changed, 82 insertions(+), 24 deletions(-)

diff --git a/traitlets/tests/test_traitlets.py b/traitlets/tests/test_traitlets.py
index 87951711..e84c91fb 100644
--- a/traitlets/tests/test_traitlets.py
+++ b/traitlets/tests/test_traitlets.py
@@ -563,7 +563,6 @@ class A(HasTraits):
             bar = Int().tag(type='a', obj=u)
             baz = Int().tag(type='z')
 
-
         a = A()
 
         def _test_observer1(change):
@@ -626,6 +625,57 @@ def _test_observer(change):
         a.bar = 2
         self.assertEqual(a.foo, 0)
 
+    def test_validate_via_tags(self):
+
+        def _domain_like(x):
+            return isinstance(x, (tuple, list)) and len(x) == 2
+
+        class A(HasTraits):
+            foo = Int().tag(domain=(1, 11))
+            bar = Int().tag(domain=(4, 8))
+            baz = Int().tag(domain=None)
+
+            @validate(tags={'domain': lambda x: _domain_like(x)})
+            def _domain_type_coecer(self, prop):
+                d = prop.trait.metadata['domain']
+                if prop.value <= d[0]:
+                    return d[0]
+                elif prop.value >= d[1]:
+                    return d[1]-1
+                else:
+                    return prop.value
+
+        a = A()
+
+        a.foo = 0
+        self.assertEqual(a.foo, 1)
+        a.foo = 11
+        self.assertEqual(a.foo, 10)
+        a.foo = 6
+        self.assertEqual(a.foo, 6)
+
+        a.bar = 0
+        self.assertEqual(a.bar, 4)
+        a.bar = 11
+        self.assertEqual(a.bar, 7)
+        a.bar = 6
+        self.assertEqual(a.bar, 6)
+
+    def test_default_via_tags(self):
+
+        class A(HasTraits):
+            foo = Int().tag(type='a')
+            bar = Int().tag(type='a')
+            baz = Int().tag(type='b')
+
+            @default(tags={'type': 'a'})
+            def _a_type_default(self):
+                return 1
+
+        a = A()
+        self.assertEqual(a.foo, 1)
+        self.assertEqual(a.bar, 1)
+        self.assertEqual(a.baz, 0)
 
     def test_subclass(self):
 
diff --git a/traitlets/traitlets.py b/traitlets/traitlets.py
index 2586e699..5d7463f4 100644
--- a/traitlets/traitlets.py
+++ b/traitlets/traitlets.py
@@ -66,7 +66,6 @@
 # Basic classes
 #-----------------------------------------------------------------------------
 
-
 Undefined = Sentinel('Undefined', 'traitlets',
 '''
 Used in Traitlets to specify that no defaults are set in kwargs
@@ -182,15 +181,13 @@ def parse_notifier_name(names):
         return []
     elif names is All or isinstance(names, six.string_types):
         return [names]
+    elif not names or All in names:
+        return [All]
     else:
-        try:
-            names = list(names)
-        except:
-            raise TypeError("could not coerce to 'list'")
         for n in names:
-            if n is not All and not isinstance(n, six.string_types):
-                raise ValueError("names must be strings or %r" % All)
-        return names
+            if not isinstance(n, six.string_types):
+                raise TypeError("names must be strings, not %s" % n)
+        return list(names)
 
 
 def parse_notifier_tags(obj, tags):
@@ -203,10 +200,17 @@ def parse_notifier_tags(obj, tags):
     tags: dict
         The tags being converted to trait names
     """
+    if isinstance(obj, HasTraits):
+        method = obj.trait_names
+    elif issubclass(obj, HasTraits):
+        method = obj.class_trait_names
+    else:
+        raise TypeError("Expected an instance or class from a HasTraits subclass")
+
     if tags is None or not len(tags):
         return []
     else:
-        return list(obj.trait_names(**tags))
+        return list(method(**tags))
 
 
 class _SimpleTest:
@@ -910,13 +914,13 @@ def __get__(self, inst, cls=None):
 class TraitEventHandler(EventHandler):
 
     metadata = {}
-    trait_names = ()
+    trait_names = []
 
     def __init__(self, names, tags):
+        if names: self.trait_names = parse_notifier_name(names)
         if tags: self.metadata = tags
-        if names: self.trait_names = names
 
-    def register(self, inst, names=None):
+    def register(self, inst):
         """Associate this event with traits on an instance"""
         pass
 
@@ -937,12 +941,11 @@ def event_of(self, obj, names=None):
         -------
         A ``set`` of trait names
         """
-        named = parse_notifier_name(self.trait_names)
         tagged = parse_notifier_tags(obj, self.metadata)
         if names is not None:
-            return set(names).intersection(named + tagged)
+            return set(names).intersection(self.trait_names + tagged)
         else:
-            return set(named + tagged)
+            return set(self.trait_names + tagged)
 
     def __eq__(self, other):
         if isinstance(other, TraitEventHandler):
@@ -1416,19 +1419,24 @@ def unobserve_all(self, name=All, type=All):
             self._trait_notifiers = {}
             self._static_trait_notifiers = []
         else:
-            names = self.trait_names() if name is All else [name]
-            try:
-                for n in self.trait_names():
-                    types = self._trait_notifiers[n] if type is All else [type]
-                    for t in types:
+            for n in self._trait_notifiers if name is All else [name]:
+                if type is All:
+                    try:
+                        tnames = self._trait_notifiers[n]
+                    except:
+                        continue
+                else:
+                    tnames = [type]
+                for t in tnames:
+                    try:
                         handlers = self._trait_notifiers[n][t]
+                    except KeyError:
+                        pass
+                    else:
                         del self._trait_notifiers[n][t]
                         for h in handlers:
                             if h.name is None:
                                 self._static_trait_notifiers.remove(h)
-            except KeyError:
-                pass
-
 
     def _register_validator(self, handler, names):
         """Setup a handler to be called when a trait should be cross validated.