Add type-checking code to Node constructor (#44)

graph_def_editor/node.py

@@ -21,7 +21,7 @@
 import tensorflow.compat.v1 as tf
 import sys
 if sys.version >= '3':
-  from typing import Tuple, List, Iterable, Any, AbstractSet
+  from typing import Tuple, List, Iterable, Any, AbstractSet, Type
 
 from graph_def_editor import graph, tensor, util
 
@@ -42,6 +42,20 @@
     "Node",
 ]
 
+def _type_check(obj: Any, expected_type: Type, arg_name: str):
+  """
+  Subroutine to validate the type of a function argument.
+
+  Args:
+      obj: Argument to validate
+      expected_type: Expected type of `obj`
+      arg_name: Name of the function argument where the caller passed `obj`
+  """
+  if not isinstance(obj, expected_type):
+    raise TypeError("'{}' argument should be of type {}, but got object of "
+                    "type {} instead. Value received was {}."
+                    "".format(arg_name, expected_type, type(obj), obj))
+
 
 class Node(object):
   """
@@ -50,11 +64,11 @@ class Node(object):
   tf.NodeDef protobuf on demand.
   """
   def __init__(self,
-               g, # type: graph.Graph
-               node_id, # type: int
-               name, # type: int
-               op_name, # type: str
-               device = "" # type: str
+               g,  # type: graph.Graph
+               node_id,  # type: int
+               name,  # type: str
+               op_name,  # type: str
+               device=""  # type: str
                ):
     """
     This constructor should only be called from methods of the Graph
@@ -69,6 +83,11 @@ def __init__(self,
       device: TensorFlow device specification string indicating where this node
         should be located. Default value of "" means "use the default device"
     """
+    _type_check(g, graph.Graph, "g")
+    _type_check(node_id, int, "node_id")
+    _type_check(name, str, "name")
+    _type_check(op_name, str, "op_name")
+    _type_check(device, str, "device")
     self._graph = g
     self._id = node_id
     self._name = name