In C++11, is it possible to do something similar to the following?
template<typename T, size_t N>
void foo(array<T, N> src) { ... }
...
foo({1, 2, 3})
I'm currently running GCC 4.8.
Yes, I managed to get the following work (since you allow something similar):
template<typename T, size_t N>
void foo(array<T, N> src) { ... }
...
foo('a', 'b');
foo(1, 2, 3);
Here is how:
#include <array>
#include <iostream>
#include <utility>
using namespace std;
template<typename T, unsigned long N>
void foo(array<T,N> src) {
for (auto e : src)
cout << e << endl;
}
template<class T, class... Tail>
auto make_array(T head, Tail... tail) -> std::array<T, 1 + sizeof...(Tail)>
{
std::array<T, 1 + sizeof...(Tail)> a = {{ head, tail ... }};
return a;
}
template<class T, class... Tail>
void foo(T&& head, Tail&&... values) {
foo(make_array(std::forward<T>(head), std::forward<Tail>(values)...));
}
int main() {
foo('a', 'b');
foo(1, 2, 3);
}
I have tested this with gcc 4.7.2 and with clang 3.4 (trunk 184647), they work as expected.
Here is an online version at Stacked-Crooked. However, this code fails to compile at Ideone. Since I was unable to figure out the options passed to the compiler at Ideone, I've given up on that site.
I have shamelessly stolen the make_array function from @Pavel Minaev's answer to the How to emulate C array initialization “int arr[] = { e1, e2, e3, … }” behaviour with std::array? question. The other make_array suggestions caused compile errors that I couldn't fix.
This make_array function has limitations, please read the entire post; in particular the discussion std::array - if only it knew its size on comp.lang.c++.moderated is referenced. Apparently, getting a reasonable make_array is quite tricky. I wouldn't recommend the simple-minded make_array in this answer to be used in production code.
You wouldn't have any problems if the size was a template argument to std::initializer_list. Hence the question Why is the size not a template argument of std::initializer_list?