Fixed a gotcha where inadvertently calling list() on a

      :class:`.ColumnElement` would go into an endless loop, if
      :meth:`.ColumnOperators.__getitem__` were implemented.
      A new NotImplementedError is emitted via ``__iter__()``.

1 files changed, 5 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql/operators.py b/lib/sqlalchemy/sql/operators.py
index 88f56e5ec..7513c0b82 100644
--- a/lib/sqlalchemy/sql/operators.py
+++ b/lib/sqlalchemy/sql/operators.py
@@ -310,6 +310,11 @@ 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.