[Python-checkins] r84246 - in python/branches/release31-maint: Doc/library/operator.rst

[benjamin.peterson]

Author: benjamin.peterson
Date: Sat Aug 21 22:17:36 2010
New Revision: 84246

Log:
Merged revisions 84242-84244 via svnmerge from 
svn+ssh://pythondev@svn.python.org/python/branches/py3k

........
  r84242 | benjamin.peterson | 2010-08-21 15:01:28 -0500 (Sat, 21 Aug 2010) | 1 line
  
  indent properly
........
  r84243 | benjamin.peterson | 2010-08-21 15:03:15 -0500 (Sat, 21 Aug 2010) | 1 line
  
  fix more indentation
........
  r84244 | benjamin.peterson | 2010-08-21 15:08:36 -0500 (Sat, 21 Aug 2010) | 1 line
  
  provide sample implementations for attrgetter and methodcaller
........


Modified:
   python/branches/release31-maint/   (props changed)
   python/branches/release31-maint/Doc/library/operator.rst

Modified: python/branches/release31-maint/Doc/library/operator.rst
==============================================================================
--- python/branches/release31-maint/Doc/library/operator.rst	(original)
+++ python/branches/release31-maint/Doc/library/operator.rst	Sat Aug 21 22:17:36 2010
@@ -333,7 +333,23 @@
    attribute is requested, returns a tuple of attributes. After,
    ``f = attrgetter('name')``, the call ``f(b)`` returns ``b.name``.  After,
    ``f = attrgetter('name', 'date')``, the call ``f(b)`` returns ``(b.name,
-   b.date)``.
+   b.date)``.  Equivalent to::
+
+      def attrgetter(*items):
+          if len(items) == 1:
+              attr = items[0]
+              def g(obj):
+                  return resolve_attr(obj, attr)
+          else:
+              def g(obj):
+                  return tuple(resolve_att(obj, attr) for attr in items)
+          return g
+
+      def resolve_attr(obj, attr):
+          for name in attr.split("."):
+              obj = getattr(obj, name)
+          return obj
+
 
    The attribute names can also contain dots; after ``f = attrgetter('date.month')``,
    the call ``f(b)`` returns ``b.date.month``.
@@ -344,15 +360,15 @@
    operand's :meth:`__getitem__` method.  If multiple items are specified,
    returns a tuple of lookup values.  Equivalent to::
 
-        def itemgetter(*items):
-            if len(items) == 1:
-                item = items[0]
-                def g(obj):
-                    return obj[item]
-            else:
-                def g(obj):
-                    return tuple(obj[item] for item in items)
-            return g
+      def itemgetter(*items):
+          if len(items) == 1:
+              item = items[0]
+              def g(obj):
+                  return obj[item]
+          else:
+              def g(obj):
+                  return tuple(obj[item] for item in items)
+          return g
 
    The items can be any type accepted by the operand's :meth:`__getitem__`
    method.  Dictionaries accept any hashable value.  Lists, tuples, and
@@ -369,12 +385,12 @@
    Example of using :func:`itemgetter` to retrieve specific fields from a
    tuple record:
 
-       >>> inventory = [('apple', 3), ('banana', 2), ('pear', 5), ('orange', 1)]
-       >>> getcount = itemgetter(1)
-       >>> map(getcount, inventory)
-       [3, 2, 5, 1]
-       >>> sorted(inventory, key=getcount)
-       [('orange', 1), ('banana', 2), ('apple', 3), ('pear', 5)]
+      >>> inventory = [('apple', 3), ('banana', 2), ('pear', 5), ('orange', 1)]
+      >>> getcount = itemgetter(1)
+      >>> map(getcount, inventory)
+      [3, 2, 5, 1]
+      >>> sorted(inventory, key=getcount)
+      [('orange', 1), ('banana', 2), ('apple', 3), ('pear', 5)]
 
 
 .. function:: methodcaller(name[, args...])
@@ -383,7 +399,12 @@
    additional arguments and/or keyword arguments are given, they will be given
    to the method as well.  After ``f = methodcaller('name')``, the call ``f(b)``
    returns ``b.name()``.  After ``f = methodcaller('name', 'foo', bar=1)``, the
-   call ``f(b)`` returns ``b.name('foo', bar=1)``.
+   call ``f(b)`` returns ``b.name('foo', bar=1)``.  Equivalent to::
+
+      def methodcaller(name, *args, **kwargs):
+          def caller(obj):
+              return getattr(obj, name)(*args, **kwargs)
+          return caller
 
 
 .. _operator-map: