Add a decorator to enforce function be called with keyworded args (only).

Change: 141373569

tensorflow/python/BUILD

@@ -244,6 +244,15 @@ py_test(
     ],
 )
 
+py_test(
+    name = "keyword_args_test",
+    srcs = ["util/keyword_args_test.py"],
+    srcs_version = "PY2AND3",
+    deps = [
+        "//tensorflow:tensorflow_py",
+    ],
+)
+
 cc_library(
     name = "python_op_gen",
     srcs = ["framework/python_op_gen.cc"],

tensorflow/python/util/keyword_args.py

@@ -0,0 +1,52 @@
+# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+
+"""Keyword args functions."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import functools
+
+from tensorflow.python.util import decorator_utils
+
+
+def keyword_args_only(func):
+  """Decorator for marking specific function accepting keyword args only.
+
+  This decorator raises a `ValueError` if the input `func` is called with any
+  non-keyword args. This prevents the caller from providing the arguments in
+  wrong order.
+
+  Args:
+    func: The function or method needed to be decorated.
+
+  Returns:
+    Decorated function or method.
+
+  Raises:
+    ValueError: If `func` is not callable.
+  """
+
+  decorator_utils.validate_callable(func, "keyword_args_only")
+  @functools.wraps(func)
+  def new_func(*args, **kwargs):
+    """Keyword args only wrapper."""
+    if args:
+      raise ValueError(
+          "Must use keyword args to call {}.".format(func.__name__))
+    return func(**kwargs)
+  return new_func

tensorflow/python/util/keyword_args_test.py

@@ -0,0 +1,51 @@
+# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Keyword args tests."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import tensorflow as tf
+from tensorflow.python.util import keyword_args
+
+
+class KeywordArgsTest(tf.test.TestCase):
+
+  def test_keyword_args_only(self):
+    def func_without_decorator(a, b):
+      return a+b
+
+    @keyword_args.keyword_args_only
+    def func_with_decorator(a, b):
+      return func_without_decorator(a, b)
+
+    self.assertEqual(3, func_without_decorator(1, 2))
+    self.assertEqual(3, func_without_decorator(a=1, b=2))
+    self.assertEqual(3, func_with_decorator(a=1, b=2))
+
+    # Providing non-keyword args should fail.
+    with self.assertRaisesRegexp(
+        ValueError, "Must use keyword args to call func_with_decorator."):
+      self.assertEqual(3, func_with_decorator(1, 2))
+
+    # Partially providing keyword args should fail.
+    with self.assertRaisesRegexp(
+        ValueError, "Must use keyword args to call func_with_decorator."):
+      self.assertEqual(3, func_with_decorator(1, b=2))
+
+
+if __name__ == "__main__":
+  tf.test.main()