Restrict variadic template arguments

Question

Can we restrict variadic template arguments to a certain type? I.e., achieve something like this (not real C++ of course):

struct X {};

auto foo(X... args)
         


        

Answer 1

You already have it since C++11 standard.

A simple std::array (special case of std::tuple where all the tuple elements share the same type) will be sufficient.

However, if you want to use it in a template function, you may better use an ´std::initializer_list` like in the following example:

template< typename T >
void foo( std::initializer_list elements );

This is a really simple solution which solves your problem. Using variadic template arguments is an option too, but adds unnecessary complexity to your code. Remember that your code should be readable by others, including yourself after some time.