Merging in latest boto.

boto/sdb/db/model.py

Index: boto/sdb/db/model.py
diff --git a/boto/sdb/db/model.py b/boto/sdb/db/model.py
index 18bec4b95cd144981a7ea32a363bfc8d91ef176a..eab82763f9bdf53e39fd5b8c03a4edb8bfeb2a4c 100644
--- a/boto/sdb/db/model.py
+++ b/boto/sdb/db/model.py
@@ -187,10 +187,56 @@ class Model(object):
             self._loaded = False
             self._manager.load_object(self)
 
-    def put(self):
-        self._manager.save_object(self)
+    def put(self, expected_value=None):
+        """
+        Save this object as it is, with an optional expected value
+
+        :param expected_value: Optional tuple of Attribute, and Value that 
+            must be the same in order to save this object. If this 
+            condition is not met, an SDBResponseError will be raised with a
+            Confict status code.
+        :type expected_value: tuple or list
+        :return: This object
+        :rtype: :class:`boto.sdb.db.model.Model`
+        """
+        self._manager.save_object(self, expected_value)
+        return self
 
     save = put
+
+    def put_attributes(self, attrs):
+        """
+        Save just these few attributes, not the whole object
+
+        :param attrs: Attributes to save, key->value dict
+        :type attrs: dict
+        :return: self
+        :rtype: :class:`boto.sdb.db.model.Model`
+        """
+        assert(isinstance(attrs, dict)), "Argument must be a dict of key->values to save"
+        for prop_name in attrs:
+            value = attrs[prop_name]
+            prop = self.find_property(prop_name)
+            assert(prop), "Property not found: %s" % prop_name
+            self._manager.set_property(prop, self, prop_name, value)
+        self.reload()
+        return self
+
+    def delete_attributes(self, attrs):
+        """
+        Delete just these attributes, not the whole object.
+
+        :param attrs: Attributes to save, as a list of string names
+        :type attrs: list
+        :return: self
+        :rtype: :class:`boto.sdb.db.model.Model`
+        """
+        assert(isinstance(attrs, list)), "Argument must be a list of names of keys to delete."
+        self._manager.domain.delete_attributes(self.id, attrs)
+        self.reload()
+        return self
+
+    save_attributes = put_attributes
         
     def delete(self):
         self._manager.delete_object(self)