Add __next__(), next() to ResultProxyreview/mike_bayer/ticket_4077

Added ``__next__()`` and ``next()`` methods to :class:`.ResultProxy`,
so that the ``next()`` builtin function works on the object directly.
:class:`.ResultProxy` has long had an ``__iter__()`` method which already
allows it to respond to the ``iter()`` builtin.   The implementation
for ``__iter__()`` is unchanged, as performance testing has indicated
that iteration using a ``__next__()`` method with ``StopIteration``
is about 20% slower in both Python 2.7 and 3.6.

Change-Id: I70569a4c48ad85a3c21a7ad422f270a559926cfb
Fixes: #4077

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/sqlalchemy/engine/result.py b/lib/sqlalchemy/engine/result.py
index 3aae932f2..79f362500 100644
--- a/lib/sqlalchemy/engine/result.py
+++ b/lib/sqlalchemy/engine/result.py
@@ -862,6 +862,8 @@ class ResultProxy(object):
             self.closed = True
 
     def __iter__(self):
+        """Implement iteration protocol."""
+
         while True:
             row = self.fetchone()
             if row is None:
@@ -869,6 +871,20 @@ class ResultProxy(object):
             else:
                 yield row
 
+    def __next__(self):
+        """Implement the next() protocol.
+
+        .. versionadded:: 1.2
+
+        """
+        row = self.fetchone()
+        if row is None:
+            raise StopIteration()
+        else:
+            return row
+
+    next = __next__
+
     @util.memoized_property
     def inserted_primary_key(self):
         """Return the primary key for the row just inserted.