Static arrays at compile time in C++

Question

I was wondering if its possible to make the following answer more generic, in the sense that the type of the array be templated instead of just unsigned:

I\'ve enclosed

Answer 1

It helps if you indent the struct. The problem is that you are defining the data static member variable inside the Array struct. But it should be at namespace scope:

template<typename ArrayType>
struct Array
{
    template<ArrayType... args> struct ArrayHolder {
        static const ArrayType data[sizeof...(args)];
    };

    template<size_t N, template<size_t> class F, ArrayType... args> 
        struct generate_array_impl {
            typedef typename generate_array_impl<N-1, F, F<N>::value, args...>::result result;
        };

    template<template<size_t> class F, ArrayType... args> 
        struct generate_array_impl<0, F, args...> {
            typedef ArrayHolder<F<0>::value, args...> result;
        };

    template<size_t N, template<size_t> class F> 
        struct generate_array {
            typedef typename generate_array_impl<N-1, F>::result result;
        };
};

template<typename ArrayType> template<ArrayType... args> 
        const ArrayType Array<ArrayType>::ArrayHolder<args...>::data[sizeof...(args)] = { args... };

Answer 2

I don't think the expression like 'template ' is a valid usage of C++11 variadic templates.

It can be of two forms as I understand:

1. template <typename... args> : variable number of generic type parameters
2. template <int... args> : variable number of integer(non-type) parameters

Refer to this wikipedia article for variadic templates.

Answer 3

Erm... Why don't you just use std::vector? Or if you want a non-resiable array, then use the equivalent type in boost?