Add some comments.

src/ngraph/except.hpp

@@ -21,6 +21,7 @@ namespace ngraph
     /// Base error for ngraph runtime errors.
     struct ngraph_error : std::runtime_error
     {
+        
         explicit ngraph_error(const std::string& what_arg)
             : std::runtime_error(what_arg)
         {

src/ngraph/parameter.hpp

@@ -23,13 +23,16 @@ namespace ngraph
     class Function;
     
     /**
-        ** One parameter of a function. Within the function's graph
-        ** the parameter is a node that represents the argument in a call.
-        **/
+     ** Parameters are nodes that represent the arguments that will be passed to user-defined functions.
+     ** Function creation requires a sequence of parameters.
+     ** Basic graph operations do not need parameters attached to a function.
+     **/
     class Parameter : public Node
     {
         friend class Function;
     protected:
+        // Called by the Function constructor to associate this parameter with the function.
+        // It is an error to try to associate a parameter with more than one function.
         void assign_function(Function* function, size_t index);
 
     public:
@@ -46,7 +49,9 @@ namespace ngraph
 
     namespace op
     {
+        /// Factory for frameworks
         std::shared_ptr<ngraph::Parameter> parameter(const ValueType::ptr& value_type=nullptr);
+        /// Convenience factory for tests
         std::shared_ptr<ngraph::Parameter> parameter(const ngraph::element::Type element_type, const Shape& shape);
     }
 }

test/build_graph.cpp

@@ -22,23 +22,17 @@ using namespace ngraph;
 TEST(build_graph, build_simple)
 {
     // Function with 4 parameters
-    auto cluster_0 = make_shared<Function>(4);
-    cluster_0->result()->type(element::float32_t, {32, 3});
-    cluster_0->parameter(0)->type(element::float32_t, {7, 3});
-    cluster_0->parameter(1)->type(element::float32_t, {3});
-    cluster_0->parameter(2)->type(element::float32_t, {32, 7});
-    cluster_0->parameter(3)->type(element::float32_t, {32, 7});
-    auto arg3 = cluster_0->parameter(3);
+    auto arg0 = op::parameter(element::float32_t, {7, 3});
+    auto arg1 = op::parameter(element::float32_t, {3});
+    auto arg2 = op::parameter(element::float32_t, {32, 7});
+    auto arg3 = op::parameter(element::float32_t, {32, 7});
     auto broadcast_1 = op::broadcast(arg3, {10, 32, 7}, {0});
-    auto arg2        = cluster_0->parameter(2);
-    auto arg0        = cluster_0->parameter(0);
     auto dot = op::dot(arg2, arg0);
     ASSERT_EQ(dot->arguments()[0], arg2);
     ASSERT_EQ(dot->arguments()[1], arg0);
-    // Function returns tuple of dot and broadcast_1.
-    cluster_0->result()->value(dot);
 
-    ASSERT_EQ(cluster_0->result()->value(), dot);
+    auto cluster_0 = op::function(dot, {arg0, arg1, arg2, arg3});
+    ASSERT_EQ(cluster_0->result(), dot);
 }
 
 // Check upcasting from ValueType.
@@ -62,20 +56,14 @@ TEST(build_graph, as_type)
 // Check node comparisons
 TEST(build_graph, node_comparison)
 {
-    auto fun = make_shared<Function>(3);
-    fun->parameter(0)->type(element::float32_t, {32, 3});
-    fun->parameter(1)->type(element::float32_t, {3});
-    fun->parameter(2)->type(element::float32_t, {32});
-    auto arg0 = fun->parameter(0);
-    auto arg1 = fun->parameter(1);
-    auto arg2 = fun->parameter(2);
+    auto arg0 = op::parameter(element::float32_t, {32, 3});
+    auto arg1 = op::parameter(element::float32_t, {3});
+    auto arg2 = op::parameter(element::float32_t, {32});
 
     auto dot = op::dot(arg0, arg1);
     auto add = op::add(dot, arg2);
 
-    auto pattern = make_shared<Function>(1);
-    pattern->parameter(0)->type(element::float32_t, {});
-    auto parg = pattern->parameter(0);
+    auto parg = op::parameter(element::float32_t, {});
     auto pattern_dot = op::dot(parg, parg);
     ASSERT_TRUE(pattern_dot->is_same_op_type(dot)); 
     // TODO This passes because typeid is not behaving as documented.