make_unique and perfect forwarding

Question

Why is there no std::make_unique function template in the standard C++11 library? I find

std::unique_ptr p(new SomeUs         


        

Answer 1

In C++11 ... is used (in template code) for "pack expansion" too.

The requirement is that you use it as a suffix of an expression containing an unexpanded pack of parameters, and it will simply apply the expression to each of the elements of the pack.

For example, building on your example:

std::forward(args)... -> std::forward(1), std::forward(2),
                                                     std::forward(3)

std::forward(args...) -> std::forward(1,2,3)

The latter being incorrect I think.

Also, pack of arguments may not be passed to a function unexpanded. I am unsure about a pack of template parameters.