CODEWITHSUNDEEP
c++templatesvariadic-templates
tambre
tambre

Reputation: 4853

Using n arguments from Args... starting from position m

Say I have different functions, which have a variable number of arguments. The first argument is always a pointer obtained through other means. All other arguments I obtain through another template using template pack expansion.
Template that I use for calling these functions is as follows:

template<typename RT, typename... Args>
inline RT call(RT(*function)(Args...))
{
    return function(pointer_from_somewhere, bind_argument<Args>::get_arg()...);
}

This obviously doesn't compile, as it performs template expansion for all arguments, thus there being too many arguments.
Since I always obtain the first argument through other means, how would I do template pack expansion for sizeof...(Args) - 1 arguments, starting from the 2nd argument?

EDIT:
While the template is slimmed down for demonstration purposes, it might be relevant, that the 1st argument (the pointer) is reinterpret_cast'ed always to the type of first argument. I use std::tuple_element<0, std::tuple<Args...>>::type for finding out the type of the 1st argument.

Upvotes: 1

Views: 71

Answers (1)

marom
marom

Reputation: 5230

Is this what you are looking for?

template<typename RT, typename A0, typename... Args>
inline RT call(RT(*function)(A0, Args...))
{
    return function(pointer_from_somewhere, bind_argument<Args>::get_arg()...);
}

Upvotes: 2

Related Questions