Initialize static std::map with unique_ptr as value

Question

How can one initialize static map, where value is std::unique_ptr?

static void f()
{
    static std::map&         


        

Answer 1

Writing bespoke crestion code seems boring and gets in the way of clarity.

Here is reasonably efficient generic container initialization code. It stores your data in a temporary std::array like an initializer list does, but it moves out instead of making it const.

The make_map takes an even number of elements, the first being key the second value.

template
struct make_container_t{
  std::array elements;
  template
  operator Container()&&{
    return {
      std::make_move_iterator(begin(elements)),
      std::make_move_iterator(end(elements))
    };
  }
};
template
make_container_t
make_container( E0 e0, Es... es ){
  return {{{std::move(e0), std::move(es)...}}};
}

namespace details{
  template
  make_container_t,sizeof...(Is)>
  make_map( std::index_sequence, std::tuple ts ){
    return {{{
      std::make_pair(
        std::move(std::get(ts)),
        std::move(std::get(ts))
      )...
    }}};
  }
}
template
auto make_map( Es... es ){
  static_assert( !(sizeof...(es)&1), "key missing a value?  Try even arguments.");
  return details::make_map(
    std::make_index_sequence{},
    std::tie( es... )
  );
}

This should reduce it to:

static std::map> bob = 
  make_map(0, std::make_unique());

... barring typos.

Live example.