C++ variadic template example

Complete example with variadic templates

This is the least viable and one of the most simple examples on how to use C++11 Variadic Templates. This sample has been tested with Microsoft Visual Studio 2015 and GCC 4.7.3.

The code is also available at Github

This example will use perfect forwarding with variadic templates to create a class wrapper around a structure, which again call the correct constructors in the structure.

//=================================================================
//	VariadicTemplate.cpp:
//=================================================================

#include <iostream>
#include <memory>
#include <type_traits>

struct SomeStruct
{
	SomeStruct()
	{
		std::cout << "SomeStruct()\n";
	}

	SomeStruct(int a)
	{
		std::cout << "SomeStruct(int a)\n";
	}

	SomeStruct(const std::string & str)
	{
		std::cout << "SomeStruct(const std::string & str)\n";
	}

	SomeStruct(const std::string & str, int a)
	{
		std::cout << 
			"SomeStruct(const std::string & str, int a)\n";
	}

};


template<typename T>
class ClassWrapper
{
	public:
		typedef T					type;
		typedef std::unique_ptr<T>	type_ptr;
		typedef ClassWrapper<T>		this_type;

	public:
		template<typename ... Args>
		static type_ptr Create(Args&&...args)
		{
			return type_ptr(
				new T(std::forward<Args>(args)...)
			);
		}

};

int main(int args, char ** argv, char ** arge)
{
	// Create a typedef to safe typing
	typedef ClassWrapper<SomeStruct>	CWSS;

	// Exercise the different SomeStruct 
	// constructors (ctor) through ClassWrapper  
	auto p1 = CWSS::Create();
	auto p2 = CWSS::Create(123);
	auto p3 = CWSS::Create("string");
	auto p4 = CWSS::Create("string", 234);

	/*
	Output should be:
	SomeStruct()
	SomeStruct(int a)
	SomeStruct(const std::string & str)
	SomeStruct(const std::string & str, int a)
	*/

	return 0;
}

Comments

Any comments? Create a new discussion on GitHub.

There used to be an inline comment form here, but it was removed.

Complete example with variadic templates

See Also

Comments