[Python-checkins] peps: Describe __members__ instead of __aliases__. +a few additional touch-ups

[eli.bendersky]

http://hg.python.org/peps/rev/54ec32489684
changeset:   4877:54ec32489684
user:        Eli Bendersky <eliben at gmail.com>
date:        Wed May 08 20:32:27 2013 -0700
summary:
  Describe __members__ instead of __aliases__. +a few additional touch-ups

files:
  pep-0435.txt |  31 ++++++++++++++++++++++---------
  1 files changed, 22 insertions(+), 9 deletions(-)


diff --git a/pep-0435.txt b/pep-0435.txt
--- a/pep-0435.txt
+++ b/pep-0435.txt
@@ -59,16 +59,17 @@
 of not allowing to subclass enums [6]_, unless they define no enumeration
 members [7]_.
 
+
 Motivation
 ==========
 
 *[Based partly on the Motivation stated in PEP 354]*
 
 The properties of an enumeration are useful for defining an immutable, related
-set of constant values that have a defined sequence but no inherent semantic
-meaning.  Classic examples are days of the week (Sunday through Saturday) and
-school assessment grades ('A' through 'D', and 'F').  Other examples include
-error status values and states within a defined process.
+set of constant values that may or may not have a semantic meaning.  Classic
+examples are days of the week (Sunday through Saturday) and school assessment
+grades ('A' through 'D', and 'F').  Other examples include error status values
+and states within a defined process.
 
 It is possible to simply define a sequence of values of some other basic type,
 such as ``int`` or ``str``, to represent discrete arbitrary values.  However,
@@ -193,7 +194,8 @@
 
 However, two enum members are allowed to have the same value.  Given two members
 A and B with the same value (and A defined first), B is an alias to A.  By-value
-lookup of the value of A and B will return A.
+lookup of the value of A and B will return A.  By-name lookup of B will also
+return A::
 
     >>> class Shape(Enum):
     ...   square = 2
@@ -213,13 +215,24 @@
     >>> list(Shape)
     [<Shape.square: 2>, <Shape.diamond: 1>, <Shape.circle: 3>]
 
-The special attribute ``__aliases__``  contains a list of all enum
-member aliases, by name::
+The special attribute ``__members__`` is an ordered dictionary mapping names
+to members.  It includes all names defined in the enumeration, including the
+aliases::
 
-    >>> Shape.__aliases__
+    >>> for name, member in Shape.__members__.items():
+    ...   name, member
+    ... 
+    ('square', <Shape.square: 2>)
+    ('diamond', <Shape.diamond: 1>)
+    ('circle', <Shape.circle: 3>)
+    ('alias_for_square', <Shape.square: 2>)
+
+The ``__members__`` attribute can be used for detailed programmatic access to
+the enumeration members.  For example, finding all the aliases::
+
+    >>> [name for name, member in Shape.__members__.items() if member.name != name]
     ['alias_for_square']
 
-
 Comparisons
 -----------
 

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