Implementation Singleton with a reference and not with a pointer with c++11 and configuration with Constructor

Hy guys,

I'm studying C++ with my personal project and I'm using the Pattern Singleton but I don't have need to pointer and I like more this reference in this post, in particular, this citation

Why does everybody want to return a singleton as a pointer? Return it as a reference seems much more logical!

I implement a Singleton with a reference but I have a problem with an initialize element when the Singleton will do created, I have initialized the element in the construction but my solution not work and I can not find the problem, now I have a question How to initialize the component inside the Singleton when it will do created?

This is my code

Singleton.h

#ifndef CONFIGURATORSINGLETON_H
#define CONFIGURATORSINGLETON_H

#include <string>

#include "Properties.h"

using namespace std;
using namespace cppproperties;

namespace spyCBlock {

  class ConfiguratorSingleton
  {
    public:
      static ConfiguratorSingleton& getInstance()
      {
        static ConfiguratorSingleton SINGLETON;

        return SINGLETON;
      }

      string getPathBlockDat() const;

      string getPathBlockDecode() const;

      string getFormatFileDecode() const;

  private:

      const string PATH_FILE = "/conf.properties";

      const string PATH_BLOCK_DAT = "PATH_BLOCK_DAT";

      const string PATH_BLOCK_DECODE = "PATH_BLOCK_DECODE";

      const string FORMAT_BLOCK_DECODE = "FORMAT_BLOCK_DECODE";

      ConfiguratorSingleton();

      Properties configuration;

      string getRootPath();

      void obligatoryVariable();

      //Variable proprieties obligatory
      string pathBlockDat;

      string pathBlockDecode;

      string formatFileDecode;

  };

}

#endif // CONFIGURATORSINGLETON_H

Singleton.cpp

#include <experimental/filesystem>
#include <glog/logging.h>

#include "ConfiguratorSingleton.h"
#include "PropertiesParser.h"

using namespace spyCBlock;


ConfiguratorSingleton::ConfiguratorSingleton()
{
  string pathConfiguration = getRootPath() + PATH_FILE;
  LOG(INFO) << "Path congiration file is: " << pathConfiguration;
  configuration = PropertiesParser::Read(pathConfiguration);

}

string ConfiguratorSingleton::getRootPath()
{
  return experimental::filesystem::current_path();
}

void ConfiguratorSingleton::obligatoryVariable()
{
  LOG(WARNING) << "Init setting variable default SpyCBlock";
  pathBlockDat = configuration.GetProperty(PATH_BLOCK_DAT);
  LOG(WARNING) << "The path of the block bitcoin core is: " << pathBlockDat;
  pathBlockDecode = configuration.GetProperty(PATH_BLOCK_DECODE);
  LOG(WARNING) << "The path of the directory for save the block decode is: " << pathBlockDecode;
  formatFileDecode = configuration.GetProperty(FORMAT_BLOCK_DECODE);
  LOG(WARNING) << "The format of the decode output is: " << formatFileDecode;
}

string ConfiguratorSingleton::getFormatFileDecode() const
{
  return formatFileDecode;
}

string ConfiguratorSingleton::getPathBlockDecode() const
{
  return pathBlockDecode;
}

string ConfiguratorSingleton::getPathBlockDat() const
{
  return pathBlockDat;
}