Associative array in C++17 for storing any data.

settings_bag.cc

#include "settings_bag.h"

std::shared_ptr<SettingsBag> SettingsBag::instance = nullptr;

SettingsBag::SettingsBag() {
}

std::shared_ptr<SettingsBag> SettingsBag::Instance() {
  if(instance == nullptr)
    instance.reset(new SettingsBag());
  return instance;
}

settings_bag.h

#ifndef SETTINGS_BAG_H
#define SETTINGS_BAG_H

#include <unordered_map>
#include <memory>
#include <string>
#include <any>

class SettingsBag {
 public: 
    template <class T>
    const T& Get(const std::string&) const;
  
    template <class T>
    void Set(const std::string&, const T&);
  
    static std::shared_ptr<SettingsBag> Instance();
  
 protected:
    SettingsBag();
  
 private:
    std::unordered_map<std::string, std::any> bag;
    static std::shared_ptr<SettingsBag> instance;
};

template <class T>
const T& SettingsBag::Get(const std::string& key) const {
  return std::any_cast<const T&>(bag.at(key));  
}

template <class T>
void SettingsBag::Set(const std::string& key, const T& value) {
  bag[key] = std::make_any<const T&>(value);
}

#endif // SETTINGS_BAG_H