What are the names of the new syntax objects added for variable templates?

Question

C ++ 11 introduced variable templates

template <typename... Args> void foo(Args... params) { cout << sizeof...(Args) << endl; } 

What are the names of Args and params ? I know that one of them (at least?) Is called a variation package of templates, but what is it? What is called another?

Answer 1

Partially citing FDIS, §14.5.3:

¹ Template parameter package is a template parameter that takes zero or more template arguments.

² Function parameter package is a function parameter that takes zero or more function arguments.

³ The package of parameters is either a package of template parameters or a package of function parameters.

⁴ A package extension consists of a template and an ellipsis, which creates zero or more template instances in the list.

So in your example

• typename... Args is a template parameter package (and therefore also a parameter package)
• Args... params - a package of function parameters (and, therefore, also a package of parameters)
• sizeof...(Args) is a package extension in which Args is a template (identifier in this context).