Add option for functions in Lambda layers to have training argument.

PiperOrigin-RevId: 239016189

tensorflow/python/keras/engine/base_layer.py

@@ -193,10 +193,7 @@ class Layer(trackable.Trackable):
     self._outbound_nodes = []
 
     call_argspec = tf_inspect.getfullargspec(self.call)
-    if 'training' in call_argspec.args:
-      self._expects_training_arg = True
-    else:
-      self._expects_training_arg = False
+    self._expects_training_arg = 'training' in call_argspec.args
 
     # Whether the `call` method can be used to build a TF graph without issues.
     self._dynamic = dynamic

tensorflow/python/keras/layers/core.py

@@ -48,6 +48,7 @@ from tensorflow.python.ops import nn_ops
 from tensorflow.python.ops import standard_ops
 from tensorflow.python.ops import variable_scope
 from tensorflow.python.util import nest
+from tensorflow.python.util import tf_inspect
 from tensorflow.python.util.tf_export import keras_export
 
 
@@ -738,6 +739,10 @@ class Lambda(Layer):
     self._trainable_weights = []
     self._non_trainable_weights = []
 
+    function_args = tf_inspect.getfullargspec(self.function).args
+    self._fn_expects_training_arg = 'training' in function_args
+    self._fn_expects_mask_arg = 'mask' in function_args
+
   @tf_utils.shape_type_conversion
   def compute_output_shape(self, input_shape):
     if self._output_shape is None:
@@ -767,10 +772,12 @@ class Lambda(Layer):
     output_shapes = tf_utils.convert_shapes(self._output_shape, to_tuples=False)
     return nest.map_structure(_add_batch, output_shapes)
 
-  def call(self, inputs, mask=None):
+  def call(self, inputs, mask=None, training=None):
     arguments = self.arguments
-    if generic_utils.has_arg(self.function, 'mask'):
+    if self._fn_expects_mask_arg:
       arguments['mask'] = mask
+    if self._fn_expects_training_arg:
+      arguments['training'] = training
     with variable_scope.variable_creator_scope(self._variable_creator):
       return self.function(inputs, **arguments)
 

tensorflow/python/keras/layers/core_test.py

@@ -204,6 +204,19 @@ class LambdaLayerTest(keras_parameterized.TestCase):
     self.assertLen(layer.trainable_weights, 1)
     self.assertEqual(layer.trainable_weights[0].name, 'lambda/multiplier:0')
 
+  def test_lambda_with_training_arg(self):
+
+    def fn(x, training=True):
+      return keras.backend.in_train_phase(x, 2 * x, training=training)
+
+    layer = keras.layers.Lambda(fn)
+    x = keras.backend.ones(())
+    train_out = layer(x, training=True)
+    eval_out = layer(x, training=False)
+
+    self.assertEqual(keras.backend.get_value(train_out), 1.)
+    self.assertEqual(keras.backend.get_value(eval_out), 2.)
+
 
 class TestStatefulLambda(keras_parameterized.TestCase):
 

tensorflow/tools/api/golden/v1/tensorflow.keras.layers.-lambda.pbtxt

@@ -118,7 +118,7 @@ tf_class {
   }
   member_method {
     name: "call"
-    argspec: "args=[\'self\', \'inputs\', \'mask\'], varargs=None, keywords=None, defaults=[\'None\'], "
+    argspec: "args=[\'self\', \'inputs\', \'mask\', \'training\'], varargs=None, keywords=None, defaults=[\'None\', \'None\'], "
   }
   member_method {
     name: "compute_mask"

tensorflow/tools/api/golden/v2/tensorflow.keras.layers.-lambda.pbtxt

@@ -118,7 +118,7 @@ tf_class {
   }
   member_method {
     name: "call"
-    argspec: "args=[\'self\', \'inputs\', \'mask\'], varargs=None, keywords=None, defaults=[\'None\'], "
+    argspec: "args=[\'self\', \'inputs\', \'mask\', \'training\'], varargs=None, keywords=None, defaults=[\'None\', \'None\'], "
   }
   member_method {
     name: "compute_mask"