[Python-checkins] peps: Make it clear that iteration order is undefined for Enums but defined for

[barry.warsaw]

http://hg.python.org/peps/rev/57f9a04d5994
changeset:   4851:57f9a04d5994
user:        Barry Warsaw <barry at python.org>
date:        Fri Apr 12 10:53:42 2013 -0400
summary:
  Make it clear that iteration order is undefined for Enums but defined for
IntEnums.

files:
  pep-0435.txt |  25 ++++++++++++++++++++++---
  1 files changed, 22 insertions(+), 3 deletions(-)


diff --git a/pep-0435.txt b/pep-0435.txt
--- a/pep-0435.txt
+++ b/pep-0435.txt
@@ -147,18 +147,37 @@
     >>> print(repr(Colors))
     <Colors {red: 1, green: 2, blue: 3}>
 
-The ``Enum`` class supports iteration.  Iteration is defined as the
-sorted order of the item values::
+The ``Enum`` class supports iteration.  Iteration order is undefined::
 
+    >>> from operator import attrgetter
+    >>> by_value = attrgetter('value')
     >>> class FiveColors(Enum):
     ...     pink = 4
     ...     cyan = 5
     ...     green = 2
     ...     blue = 3
     ...     red = 1
-    >>> [v.name for v in FiveColors]
+    >>> [v.name for v in sorted(FiveColors, by_value)]
     ['red', 'green', 'blue', 'pink', 'cyan']
 
+Iteration order over ``IntEnum`` enumerations are guaranteed to be
+sorted by value.
+
+    >>> class Toppings(IntEnum):
+    ...     anchovies = 4
+    ...     black_olives = 8
+    ...     cheese = 2
+    ...     dried_tomatoes = 16
+    ...     eggplant = 1
+
+    >>> for value in Toppings:
+    ...     print(value.name, '=', value.value)
+    eggplant = 1
+    cheese = 2
+    anchovies = 4
+    black_olives = 8
+    dried_tomatoes = 16
+
 Enumeration values are hashable, so they can be used in dictionaries and sets::
 
     >>> apples = {}

-- 
Repository URL: http://hg.python.org/peps