Make calling AbstractModule.__init__ without named arguments throw an…

… exception.

PiperOrigin-RevId: 157694146

sonnet/python/modules/base.py

@@ -112,7 +112,7 @@ class AbstractModule(object):
   sharing will not work.
   """
 
-  def __init__(self, name=None):
+  def __init__(self, _sentinel=None, name=None):  # pylint: disable=invalid-name
     """Performs the initialisation necessary for all AbstractModule instances.
 
     Every subclass of AbstractModule must begin their constructor with a call to
@@ -123,11 +123,18 @@ def __init__(self, name=None):
     variable scope. Alternatively, instantiate sub-modules in `_build`.
 
     Args:
+      _sentinel: Variable that only carries a non-None value if `__init__` was
+          called without named parameters. If this is the case, a deprecation
+          warning is issued in form of a `ValueError`.
       name: Name of this module. Used to construct the Templated build function.
 
     Raises:
       ValueError: If name is not specified.
+      ValueError: If `__init__` was called without named arguments.
     """
+    if _sentinel is not None:
+      raise ValueError("Calling AbstractModule.__init__ without named "
+                       "arguments is deprecated.")
 
     if name is None or not isinstance(name, six.string_types):
       raise ValueError("Name must be a string.")

sonnet/python/modules/base_test.py

@@ -20,7 +20,6 @@
 from __future__ import print_function
 
 from functools import partial
-
 import numpy as np
 import six
 from sonnet.python.modules import base
@@ -56,6 +55,13 @@ def _build(self, inputs):
     return tf.identity(inputs)
 
 
+class NoInitIdentityModule(base.AbstractModule):
+  """Sonnet module that doesn't call `base.AbstractModule.__init__`."""
+
+  def _build(self, inputs):
+    return tf.identity(inputs)
+
+
 class AbstractModuleTest(tf.test.TestCase):
 
   def testInitializerKeys(self):
@@ -136,6 +142,11 @@ def testSubgraphsRecording(self):
     self.assertIs(subgraphs[1].outputs, blah_outputs)
     self.assertIs(subgraphs[2].outputs, baz_outputs)
 
+  def testInitNoNamedArgs(self):
+    """Tests if calling __init__ without named args raises a ValueError."""
+    with self.assertRaises(ValueError):
+      NoInitIdentityModule("foobar")
+
 
 def _make_model_with_params(inputs, output_size):
   weight_shape = [inputs.get_shape().as_list()[-1], output_size]