Question: What is the right way of initializing a static map? Do we need a static function that will initialize it?

Answer: 
For example:

```
const std::map<LogLevel, const char*> g_log_levels_dsc =
{
    { LogLevel::Disabled, "[---]" },
    { LogLevel::Info,     "[inf]" },
    { LogLevel::Warning,  "[wrn]" },
    { LogLevel::Error,    "[err]" },
    { LogLevel::Debug,    "[dbg]" }
};

```

If map is a data member of a class, you can initialize it directly in header by the following way (since C++17):

```
// Example

template<>
class StringConverter<CacheMode> final
{
public:
    static auto convert(CacheMode mode) -> const std::string&
    {
        // validate...
        return s_modes.at(mode);
    }

private:
    static inline const std::map<CacheMode, std::string> s_modes =
        {
            { CacheMode::All, "All" },
            { CacheMode::Selective, "Selective" },
            { CacheMode::None, "None" }
            // etc
        };
}; 

```
This is similar to `PierreBdR`, without copying the map.

```
#include <map>

using namespace std;

bool create_map(map<int,int> &m)
{
  m[1] = 2;
  m[3] = 4;
  m[5] = 6;
  return true;
}

static map<int,int> m;
static bool _dummy = create_map (m);

```