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, 17 insertions, 0 deletions

diff --git a/test/sql/test_resultset.py b/test/sql/test_resultset.py
index 41092efe9..5c7108ca0 100644
--- a/test/sql/test_resultset.py
+++ b/test/sql/test_resultset.py
@@ -61,6 +61,23 @@ class ResultProxyTest(fixtures.TablesTest):
             rows.append(row)
         eq_(len(rows), 3)
 
+    def test_row_next(self):
+        users = self.tables.users
+
+        users.insert().execute(
+            {'user_id': 7, 'user_name': 'jack'},
+            {'user_id': 8, 'user_name': 'ed'},
+            {'user_id': 9, 'user_name': 'fred'},
+        )
+        r = users.select().execute()
+        rows = []
+        while True:
+            row = next(r, 'foo')
+            if row == 'foo':
+                break
+            rows.append(row)
+        eq_(len(rows), 3)
+
     @testing.requires.subqueries
     def test_anonymous_rows(self):
         users = self.tables.users