- documentation and changelog for [ticket:2601]

4 files changed, 70 insertions, 10 deletions

diff --git a/doc/build/changelog/changelog_08.rst b/doc/build/changelog/changelog_08.rst
index c472b444a..0ed67b489 100644
--- a/doc/build/changelog/changelog_08.rst
+++ b/doc/build/changelog/changelog_08.rst
@@ -7,6 +7,14 @@
     :version: 0.8.0b2
 
     .. change::
+        :tags: orm, feature
+        :tickets: 2601
+
+      Added :meth:`.KeyedTuple._asdict` and :attr:`.KeyedTuple._fields`
+      to the :class:`.KeyedTuple` class to provide some degree of compatibility
+      with the Python standard library ``collections.namedtuple()``.
+
+    .. change::
         :tags: sql, bug
         :tickets: 2631
 
diff --git a/doc/build/orm/query.rst b/doc/build/orm/query.rst
index dcd7ec40e..e5358792c 100644
--- a/doc/build/orm/query.rst
+++ b/doc/build/orm/query.rst
@@ -32,6 +32,9 @@ ORM-Specific Query Constructs
 
 .. autoclass:: sqlalchemy.orm.util.AliasedInsp
 
+.. autoclass:: sqlalchemy.util.KeyedTuple
+	:members: keys, _fields, _asdict
+
 .. autofunction:: join
 
 .. autofunction:: outerjoin
diff --git a/doc/build/orm/tutorial.rst b/doc/build/orm/tutorial.rst
index 0e954946d..fadad8551 100644
--- a/doc/build/orm/tutorial.rst
+++ b/doc/build/orm/tutorial.rst
@@ -623,7 +623,8 @@ is expressed as tuples:
     fred Fred Flinstone
 
 The tuples returned by :class:`~sqlalchemy.orm.query.Query` are *named*
-tuples, and can be treated much like an ordinary Python object. The names are
+tuples, supplied by the :class:`.KeyedTuple` class, and can be treated much like an
+ordinary Python object. The names are
 the same as the attribute's name for an attribute, and the class name for a
 class:
 
diff --git a/lib/sqlalchemy/util/_collections.py b/lib/sqlalchemy/util/_collections.py
index 244ed5c5e..af8292806 100644
--- a/lib/sqlalchemy/util/_collections.py
+++ b/lib/sqlalchemy/util/_collections.py
@@ -16,18 +16,39 @@ EMPTY_SET = frozenset()
 
 
 class KeyedTuple(tuple):
-    """tuple() subclass that adds labeled names.
+    """``tuple`` subclass that adds labeled names.
 
-    Unlike collections.namedtuple, this is
-    an ad-hoc data structure, not a factory
-    for new types.
+    E.g.::
 
-    It's pickleable in-place without the need for stack
-    frame manipulation, new KeyedTuple types can be created
-    very quickly and simply (look at the source
-    to collections.namedtuple for contrast).
+        >>> k = KeyedTuple([1, 2, 3], labels=["one", "two", "three"])
+        >>> k.one
+        1
+        >>> k.two
+        2
 
-    Is used by :class:`.Query` to return result rows.
+    Result rows returned by :class:`.Query` that contain multiple
+    ORM entities and/or column expressions make use of this
+    class to return rows.
+
+    The :class:`.KeyedTuple` exhibits similar behavior to the
+    ``collections.namedtuple()`` construct provided in the Python
+    standard library, however is architected very differently.
+    Unlike ``collections.namedtuple()``, :class:`.KeyedTuple` is
+    does not rely on creation of custom subtypes in order to represent
+    a new series of keys, instead each :class:`.KeyedTuple` instance
+    receives its list of keys in place.   The subtype approach
+    of ``collections.namedtuple()`` introduces significant complexity
+    and performance overhead, which is not necessary for the
+    :class:`.Query` object's use case.
+
+    .. versionchanged:: 0.8
+        Compatibility methods with ``collections.namedtuple()`` have been
+        added including :attr:`.KeyedTuple._fields` and
+        :meth:`.KeyedTuple._asdict`.
+
+    .. seealso::
+
+        :ref:`ormtutorial_querying`
 
     """
 
@@ -40,13 +61,40 @@ class KeyedTuple(tuple):
         return t
 
     def keys(self):
+        """Return a list of string key names for this :class:`.KeyedTuple`.
+
+        .. seealso::
+
+            :attr:`.KeyedTuple._fields`
+
+        """
+
         return [l for l in self._labels if l is not None]
 
     @property
     def _fields(self):
+        """Return a tuple of string key names for this :class:`.KeyedTuple`.
+
+        This method provides compatibility with ``collections.namedtuple()``.
+
+        .. versionadded:: 0.8
+
+        .. seealso::
+
+            :meth:`.KeyedTuple.keys`
+
+        """
         return tuple(self.keys())
 
     def _asdict(self):
+        """Return the contents of this :class:`.KeyedTuple` as a dictionary.
+
+        This method provides compatibility with ``collections.namedtuple()``,
+        with the exception that the dictionary returned is **not** ordered.
+
+        .. versionadded:: 0.8
+
+        """
         return dict((key, self.__dict__[key]) for key in self.keys())