some old changes on test_copy_elision.cpp

test_copy_elision.cpp

@@ -3,10 +3,10 @@
 #include <string>
 #include <algorithm>
 
-class copy_tracker
+struct copy_tracker
 {
 	int v;
-public:
+
 	copy_tracker()
 		: v(0)
 	{
@@ -16,7 +16,13 @@ public:
 	copy_tracker( const copy_tracker& c )
 		: v( c.v )
 	{
-		std::cout << "copy_tracker::copy_tracker( copy_tracker& c )" << std::endl;
+		std::cout << "copy_tracker::copy_tracker( const copy_tracker& c )" << std::endl;
+	}
+
+	copy_tracker( copy_tracker&& c )
+		: v( c.v )
+	{
+		std::cout << "copy_tracker::copy_tracker( copy_tracker&& c )  MOVE " << std::endl;
 	}
 
 	void use_object()
@@ -25,37 +31,123 @@ public:
 	}
 };
 
-copy_tracker copy_tracker_return_by_value2()
+template <int n>
+copy_tracker return_by_value()
+{
+	return return_by_value<n-1>();
+}
+template <>
+copy_tracker return_by_value<1>()
 {
 	return copy_tracker();
 }
 
-copy_tracker copy_tracker_return_by_value()
+template <int n>
+copy_tracker return_by_value2()
 {
-	return copy_tracker_return_by_value2();
+	copy_tracker o = return_by_value2<n-1>();
+	o.v = n;
+	return o;
+}
+template <>
+copy_tracker return_by_value2<1>()
+{
+	copy_tracker o; //return value optimization still applies.
+	o.v = 1;
+	return o;
 }
 
-void copy_tracker_pass_by_value2(copy_tracker o)
+template <int n>
+copy_tracker static_by_value()
 {
-	return o.use_object();
+	return static_by_value<n-1>();
+}
+template <>
+copy_tracker static_by_value<1>()
+{
+	static copy_tracker o; //return value optimization still applies.
+	return o;
 }
 
-void copy_tracker_pass_by_value(copy_tracker o)
+
+template <int n>
+copy_tracker move_by_value()
 {
-	return copy_tracker_pass_by_value2(o);
+	return std::move(move_by_value<n-1>());
 }
+template <>
+copy_tracker move_by_value<1>()
+{
+	return copy_tracker(); //return value optimization still applies.
+}
+
+
+template <int n>
+void pass_by_value(copy_tracker o)
+{
+	pass_by_value<n-1>(std::move(o));
+//	o.v = n;
+//	o.use_object();
+}
+template <>
+void pass_by_value<1>(copy_tracker o)
+{
+	o.use_object();
+}
+
 
 void test_copy_tracker()
 {
+	std::cout << "---------------------------------------------------------" 
+				<< std::endl << std::endl;
+	
 	std::cout << "Return by value and assign." << std::endl;
-	copy_tracker o = copy_tracker_return_by_value();
+	{ copy_tracker o = return_by_value<10>(); }
+	std::cout << "---------------------------------------------------------" 
+				<< std::endl << std::endl;
+
+	std::cout << "Return by named value and assign." << std::endl;
+	{ copy_tracker o = return_by_value2<10>(); }
+	std::cout << "---------------------------------------------------------" 
+				<< std::endl << std::endl;
+
+	std::cout << "Return static and assign." << std::endl;
+	{ copy_tracker o = static_by_value<10>(); }
+	std::cout << "---------------------------------------------------------" 
+				<< std::endl << std::endl;
+	
+	std::cout << "Move value and assign." << std::endl;
+	{ copy_tracker o = move_by_value<10>(); }
+	std::cout << "---------------------------------------------------------" 
+				<< std::endl << std::endl;
+
 	std::cout << "Pass lvalue." << std::endl;
-	copy_tracker_pass_by_value( o );
+	{ copy_tracker o = return_by_value<10>();
-	std::cout << "Pass rvalue." << std::endl;
+	  pass_by_value<1>( o ); }
-	const copy_tracker& o2 = copy_tracker_return_by_value();
+	std::cout << "---------------------------------------------------------" 
-	copy_tracker_pass_by_value2( o2 );
+				<< std::endl << std::endl;
-	std::cout << "Pass rvalue 2." << std::endl;
+
-	copy_tracker_pass_by_value2( copy_tracker_return_by_value() );
+	std::cout << "Pass by intermediately captured rvalue." << std::endl;
+	{ const copy_tracker& o = return_by_value<10>();
+	  pass_by_value<1>( o ); }
+	std::cout << "---------------------------------------------------------" 
+				<< std::endl << std::endl;
+	
+	std::cout << "Pass by intermediately captured rvalue." << std::endl;
+	{ const copy_tracker& o = return_by_value<10>();
+	  pass_by_value<1>( static_cast<copy_tracker&&>(const_cast<copy_tracker&>(o)) ); }
+	std::cout << "---------------------------------------------------------" 
+				<< std::endl << std::endl;
+
+	std::cout << "Pass rvalue directly." << std::endl;
+	{ pass_by_value<1>( return_by_value<10>() ); }
+	std::cout << "---------------------------------------------------------" 
+				<< std::endl << std::endl;
+	
+	std::cout << "Pass rvalue directly." << std::endl;
+	{ pass_by_value<2>( return_by_value<10>() ); }
+	std::cout << "---------------------------------------------------------" 
+				<< std::endl << std::endl;
 }
 
 int main ( void )