How to implement a type trait that checks whether all the elements of a parameter pack are of some concrete type T?

Asked Aug 12 '19 at 20:24

Active Aug 12 '19 at 20:25

Viewed 32 times

I want to provide a static assert that checks whether all the elements of a parameter pack are of some type T.

The client code looks like:

template <typename... Args>
void foo(Args... args)
{
    static_assert(are_all_of_the_type<int, Args...>::value);
}

Any ideas on how to implement the type trait are_all_of_the_type?

A very alike question was addressed here, yet I don't see how to use the proposed solution with a parameter pack.

edited Aug 12 '19 at 20:25

asked Aug 12 '19 at 20:24

Nestor

1

Are you okay with just doing `(std::is_same_v && ...)`? – David G Aug 12 '19 at 20:26
Tell me if this dupe has a problem. – Guillaume Racicot Aug 12 '19 at 20:26
@0x499602D2 `static_assert(std::is_same_v && ...);` doesn't compile :( (expected expression) – Nestor Aug 12 '19 at 20:35
@GuillaumeRacicot many thanks, `static_assert(std::conjunction_v...>)` works fine – Nestor Aug 12 '19 at 20:41
2

You forgot the parenthesis: `static_assert((std::is_same_v && ...))` – David G Aug 12 '19 at 20:57

0 Answers0