Question

I have a function template that must be allow only certain types. I’ve seen other questions but they used boost and primitve types. In this case, no boost, and it’s a user defined class.

Ex:

template<typename T>
myfunc(T&)
{ ... }

template<>
myfunc(Foo&)
{
   static_assert(false, "You cannot use myfunc with Foo");
}

Problem is static_assert gets called regardless of whether I call myfunc with a Foo object or not.

I just want some way for compile to stop when myfunc is called with Foo.
How can I achieve this functionality?

Answer 1

You can use std::is_same for this:

#include <type_traits>

template<typename T>
return_type myfunc(T&)
{
   static_assert(std::is_same<T, Foo>::value, "You cannot use myfunc with Foo");

   // ...
}