operator overloading as a free function (#142)

src/ngraph/descriptor/tensor.cpp

@@ -59,7 +59,7 @@ size_t Tensor::get_pool_offset() const
     return m_pool_offset;
 }
 
-std::ostream& descriptor::operator<<(std::ostream& out, const Tensor& tensor)
+std::ostream& operator<<(std::ostream& out, const Tensor& tensor)
 {
     out << "Tensor(" << tensor.get_name() << ")";
     return out;

src/ngraph/descriptor/tensor.hpp

@@ -59,8 +59,6 @@ public:
     void               set_pool_offset(size_t);
     size_t             get_pool_offset() const;
 
-    friend std::ostream& operator<<(std::ostream&, const Tensor&);
-
 protected:
     const element::Type& m_element_type;
     PrimaryTensorView*   m_primary_tensor_view;
@@ -72,3 +70,5 @@ protected:
     size_t               m_size;
     size_t               m_pool_offset;
 };
+
+std::ostream& operator<<(std::ostream&, const ngraph::descriptor::Tensor&);