[Python-checkins] cpython: revert change 87a9dff5106c: pure Enum members again evaluate to True;

[ethan.furman]

https://hg.python.org/cpython/rev/52dc28ee3c88
changeset:   99911:52dc28ee3c88
parent:      99909:87f87673af7b
user:        Ethan Furman <ethan at stoneleaf.us>
date:        Fri Jan 15 15:01:33 2016 -0800
summary:
  revert change 87a9dff5106c: pure Enum members again evaluate to True;
update Finer Points section of docs to cover boolean evaluation;
add more tests for pure and mixed boolean evaluation

files:
  Doc/library/enum.rst  |  11 ++++++++++-
  Lib/enum.py           |   3 ---
  Lib/test/test_enum.py |  17 ++++++++++++++++-
  3 files changed, 26 insertions(+), 5 deletions(-)


diff --git a/Doc/library/enum.rst b/Doc/library/enum.rst
--- a/Doc/library/enum.rst
+++ b/Doc/library/enum.rst
@@ -257,7 +257,7 @@
     >>> Color.red < Color.blue
     Traceback (most recent call last):
       File "<stdin>", line 1, in <module>
-    TypeError: '<' not supported between instances of 'Color' and 'Color'
+    TypeError: unorderable types: Color() < Color()
 
 Equality comparisons are defined though::
 
@@ -747,6 +747,15 @@
 
 .. versionchanged:: 3.5
 
+Boolean evaluation: Enum classes that are mixed with non-Enum types (such as
+:class:`int`, :class:`str`, etc.) are evaluated according to the mixed-in
+type's rules; otherwise, all members evaluate as ``True``.  To make your own
+Enum's boolean evaluation depend on the member's value add the following to
+your class::
+
+    def __bool__(self):
+        return bool(self._value_)
+
 The :attr:`__members__` attribute is only available on the class.
 
 If you give your :class:`Enum` subclass extra methods, like the `Planet`_
diff --git a/Lib/enum.py b/Lib/enum.py
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -482,9 +482,6 @@
     def __str__(self):
         return "%s.%s" % (self.__class__.__name__, self._name_)
 
-    def __bool__(self):
-        return bool(self._value_)
-
     def __dir__(self):
         added_behavior = [
                 m
diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py
--- a/Lib/test/test_enum.py
+++ b/Lib/test/test_enum.py
@@ -272,11 +272,26 @@
                 _any_name_ = 9
 
     def test_bool(self):
+        # plain Enum members are always True
         class Logic(Enum):
             true = True
             false = False
         self.assertTrue(Logic.true)
-        self.assertFalse(Logic.false)
+        self.assertTrue(Logic.false)
+        # unless overridden
+        class RealLogic(Enum):
+            true = True
+            false = False
+            def __bool__(self):
+                return bool(self._value_)
+        self.assertTrue(RealLogic.true)
+        self.assertFalse(RealLogic.false)
+        # mixed Enums depend on mixed-in type
+        class IntLogic(int, Enum):
+            true = 1
+            false = 0
+        self.assertTrue(IntLogic.true)
+        self.assertFalse(IntLogic.false)
 
     def test_contains(self):
         Season = self.Season

-- 
Repository URL: https://hg.python.org/cpython