You can use a helper class to fine tune specializations:
template <typename F>
struct wrapper
{};
template <typename Res, typename... Args>
struct wrapper<Res(Args...)>
{
static Res wrap(Res (WINAPI *f)(Args...), Args&& args...)
{
Res r = f(std::forward<Args>(args)...);
// Blah blah
return r;
}
};
template <typename... Args>
struct wrapper<void(Args...)>
{
static void wrap(void (WINAPI *f)(Args...), Args&& args...)
{
f(std::forward<Args>(args)...);
// Blah blah
}
};
Now, you can write the wrapper:
template <typename Res, typename... Args>
Res Wrap(Res (WINAPI *f)(Args...), Args&& args...)
{
return wrapper<Res(Args...)>::wrap(f, std::forward<Args>(args)...);
}
Note that it works even when Res
is void
. You’re allowed to return
an expression returning void in a function returning void.
The correct type is deduced, as in Wrap(someFunc, 5, true)
, even for functions returning void.