- merge ticket_1418 branch, [ticket:1418]

- The system of loader options has been entirely rearchitected to build
upon a much more comprehensive base, the :class:`.Load` object.  This
base allows any common loader option like :func:`.joinedload`,
:func:`.defer`, etc. to be used in a "chained" style for the purpose
of specifying options down a path, such as ``joinedload("foo").subqueryload("bar")``.
The new system supersedes the usage of dot-separated path names,
multiple attributes within options, and the usage of ``_all()`` options.
-  Added a new load option :func:`.orm.load_only`.  This allows a series
of column names to be specified as loading "only" those attributes,
deferring the rest.

1 files changed, 13 insertions, 0 deletions

diff --git a/lib/sqlalchemy/orm/base.py b/lib/sqlalchemy/orm/base.py
index f7d9dd4fe..47d8796b8 100644
--- a/lib/sqlalchemy/orm/base.py
+++ b/lib/sqlalchemy/orm/base.py
@@ -129,6 +129,19 @@ NOT_EXTENSION = util.symbol('NOT_EXTENSION')
 _none_set = frozenset([None])
 
 
+def _generative(*assertions):
+    """Mark a method as generative, e.g. method-chained."""
+
+    @util.decorator
+    def generate(fn, *args, **kw):
+        self = args[0]._clone()
+        for assertion in assertions:
+            assertion(self, fn.__name__)
+        fn(self, *args[1:], **kw)
+        return self
+    return generate
+
+
 # these can be replaced by sqlalchemy.ext.instrumentation
 # if augmented class instrumentation is enabled.
 def manager_of_class(cls):