fixed #108

src/TensorFlowNET.Core/Graphs/Graph.cs

@@ -37,15 +37,10 @@ namespace Tensorflow
         {
             _handle = c_api.TF_NewGraph();
             Status = new Status();
-        }
-
-        public Graph(IntPtr graph)
-        {
-            _handle = graph;
-            Status = new Status();
             _nodes_by_id = new Dictionary<int, Operation>();
             _nodes_by_name = new Dictionary<string, Operation>();
             _names_in_use = new Dictionary<string, int>();
+            _graph_key = $"grap-key-{ops.uid()}/";
         }
 
         public T as_graph_element<T>(T obj, bool allow_tensor = true, bool allow_operation = true)

src/TensorFlowNET.Core/Variables/RefVariable.cs

@@ -28,6 +28,8 @@ namespace Tensorflow
             TF_DataType dtype = TF_DataType.DtInvalid) : 
             base(initial_value, trainable, collections, validate_shape, caching_device, name, dtype)
         {
+            _in_graph_mode = true;
+
             _init_from_args(initial_value, trainable, collections, validate_shape, caching_device, name, dtype);
         }
 

src/TensorFlowNET.Core/ops.py.cs

@@ -174,9 +174,16 @@ namespace Tensorflow
             // outer_device_stack = None
         }
 
+        private static int uid_number = 0;
+
+        /// <summary>
+        /// A unique (within this program execution) integer.
+        /// Not thread safe
+        /// </summary>
+        /// <returns></returns>
         public static int uid()
         {
-            return 1;
+            return uid_number++;
         }
     }
 }

src/TensorFlowNET.Core/tf.cs

@@ -15,7 +15,7 @@ namespace Tensorflow
 
         public static Context context;
 
-        public static Graph g = new Graph(c_api.TF_NewGraph());
+        public static Graph g = new Graph();
 
         public static RefVariable Variable<T>(T data, string name = "", TF_DataType dtype = TF_DataType.DtInvalid)
         {

test/TensorFlowNET.UnitTest/VariableTest.cs

@@ -35,7 +35,7 @@ namespace TensorFlowNET.UnitTest
 
             using (var session = tf.Session())
             {
-                session.run(model);
+                var sm = session.run(model);
                 for(int i = 0; i < 5; i++)
                 {
                     var x1 = x + 1;