Static Global Maps in C++

I recently saw this construction which made me feel super weird:

static const std::map<int, std::string>& GetMySpecialMap() {
  static const std::map<int, std::string>* const kMap = new std::Map({
    {1, "val1"},
    {2, "val2"},
  });
  return *kMap;
}

This feels gross because the map is allocated on the heap and never destroyed. But then you realize why they do it: they want a global static map, and globals are going to stick around for the life of the program.

Here’s an alternative approach.

You can define a template that makes the static allocation on the stack instead of the heap, and it similarly never destroys itself. It looks a bit nicer because there’s not a new that you feel the creeping urge to destroy.

static const std::map<int, std::string>& GetMySpecialMap() {
  static const riegeli::NoDestructor<std::map<int, std::string>> kMap({
    {1, "val1"},
    {2, "val2"},
  });
  return *kMap;
}