- remove the ``__iter__()`` with notimplemented since it interferes

with legitimate iterable detection, [ticket:2726]

4 files changed, 36 insertions, 12 deletions

diff --git a/doc/build/changelog/changelog_08.rst b/doc/build/changelog/changelog_08.rst
index 211668867..7e8e618a4 100644
--- a/doc/build/changelog/changelog_08.rst
+++ b/doc/build/changelog/changelog_08.rst
@@ -7,6 +7,21 @@
     :version: 0.8.2
 
     .. change::
+        :tags: bug, sql
+        :tickets: 2726
+
+        Removed the "not implemented" ``__iter__()`` call from the base
+        :class:`.ColumnOperators` class, while this was introduced
+        in 0.8.0 to prevent an endless, memory-growing loop when one also
+        implements a ``__getitem__()`` method on a custom
+        operator and then calls erroneously ``list()`` on that object,
+        it had the effect of causing column elements to report that they
+        were in fact iterable types which then throw an error when you try
+        to iterate.   There's no real way to have both sides here so we
+        stick with Python best practices.  Careful with implementing
+        ``__getitem__()`` on your custom operators!
+
+    .. change::
       :tags: feature, orm
       :tickets: 2736
 
diff --git a/doc/build/changelog/changelog_09.rst b/doc/build/changelog/changelog_09.rst
index df87f397c..3c9682105 100644
--- a/doc/build/changelog/changelog_09.rst
+++ b/doc/build/changelog/changelog_09.rst
@@ -7,6 +7,21 @@
     :version: 0.9.0
 
     .. change::
+        :tags: bug, sql
+        :tickets: 2726
+
+        Removed the "not implemented" ``__iter__()`` call from the base
+        :class:`.ColumnOperators` class, while this was introduced
+        in 0.8.0 to prevent an endless, memory-growing loop when one also
+        implements a ``__getitem__()`` method on a custom
+        operator and then calls erroneously ``list()`` on that object,
+        it had the effect of causing column elements to report that they
+        were in fact iterable types which then throw an error when you try
+        to iterate.   There's no real way to have both sides here so we
+        stick with Python best practices.  Careful with implementing
+        ``__getitem__()`` on your custom operators! Also in 0.8.2.
+
+    .. change::
         :tags: feature, sql
         :tickets: 1068
 
diff --git a/lib/sqlalchemy/sql/operators.py b/lib/sqlalchemy/sql/operators.py
index 4afb3db48..128442158 100644
--- a/lib/sqlalchemy/sql/operators.py
+++ b/lib/sqlalchemy/sql/operators.py
@@ -313,11 +313,6 @@ class ColumnOperators(Operators):
         """
         return self.operate(neg)
 
-    def __iter__(self):
-        """Block calls to list() from calling __getitem__() endlessly."""
-
-        raise NotImplementedError("Class %s is not iterable" % self.__class__)
-
     def __getitem__(self, index):
         """Implement the [] operator.
 
diff --git a/test/sql/test_operators.py b/test/sql/test_operators.py
index d1db733e0..b3919d0da 100644
--- a/test/sql/test_operators.py
+++ b/test/sql/test_operators.py
@@ -15,7 +15,7 @@ from sqlalchemy.dialects import mysql, firebird, postgresql, oracle, \
         sqlite, mssql
 from sqlalchemy import util
 import datetime
-
+import collections
 from sqlalchemy import text, literal_column
 
 class LoopOperate(operators.ColumnOperators):
@@ -352,17 +352,16 @@ class ExtensionOperatorTest(fixtures.TestBase, testing.AssertsCompiledSQL):
             "x -> :x_1"
         )
 
-    def test_no_endless_list_call(self):
+    @testing.requires.python26
+    def test_op_not_an_iterator(self):
+        # see [ticket:2726]
         class MyType(UserDefinedType):
             class comparator_factory(UserDefinedType.Comparator):
                 def __getitem__(self, index):
                     return self.op("->")(index)
 
-        assert_raises_message(
-            NotImplementedError,
-            "Class <class 'sqlalchemy.schema.Column'> is not iterable",
-            list, Column('x', MyType())
-        )
+        col = Column('x', MyType())
+        assert not isinstance(col, collections.Iterable)
 
     def test_lshift(self):
         class MyType(UserDefinedType):