1 files changed, 18 insertions, 1 deletions
diff --git a/tensorflow/contrib/constrained_optimization/python/constrained_minimization_problem.py b/tensorflow/contrib/constrained_optimization/python/constrained_minimization_problem.py
index 70813fb217..41258edd90 100644
--- a/tensorflow/contrib/constrained_optimization/python/constrained_minimization_problem.py
+++ b/tensorflow/contrib/constrained_optimization/python/constrained_minimization_problem.py
@@ -72,7 +72,8 @@ class ConstrainedMinimizationProblem(object):
     else:
       proxy_constraints_shape = self.proxy_constraints.get_shape()
 
-    if (constraints_shape is None or proxy_constraints_shape is None or
+    if (constraints_shape.ndims is None or
+        proxy_constraints_shape.ndims is None or
         any([ii is None for ii in constraints_shape.as_list()]) or
         any([ii is None for ii in proxy_constraints_shape.as_list()])):
       raise ValueError(
@@ -121,3 +122,19 @@ class ConstrainedMinimizationProblem(object):
       A tensor of proxy constraint functions.
     """
     return None
+
+  # This is a property, instead of an abstract property, since it doesn't need
+  # to be overridden: if pre_train_ops returns None, then there are no ops to
+  # run before train_op.
+  @property
+  def pre_train_ops(self):
+    """Returns a list of `Operation`s to run before the train_op.
+
+    When a `ConstrainedOptimizer` creates a train_op (in `minimize`
+    `minimize_unconstrained`, or `minimize_constrained`), it will include these
+    ops before the main training step.
+
+    Returns:
+      A list of `Operation`s.
+    """
+    return None