use jsoncpp to load /de-serialise a class'es data so we can duck-type it's values not rely on hard-coded keys from the json

jsoncpp_objectducktype.cpp

// Load a Json/Yaml file into a duck-typable object not relying on typed in 
// dictionary/map keys
//

#include <iostream>
// unused #include <vector>
#include <map>
// unused #include <sstream>
// note add json_reader.cpp, json_value.cpp, jon_write.cpp to your project
#include <json/json.h>
#include <json/reader.h>
#define FMT_HEADER_ONLY 1
#define FMT_UNICODE 0
#include <spdlog/fmt/fmt.h>


/////////////////////////////////////////////////////////////////////////////////////////////////////////
class ArgsBase
{
public:
    void loadfrom(std::map<std::string, Json::Value*> variable_map, Json::Value data) {
        std::cout << "loadfrom(): data" << std::endl;
        if (data.size() > 0) {
            for (Json::Value::const_iterator itr = data.begin(); itr != data.end(); itr++) {
                // finds using each key and updates it's variable's value
                *variable_map[itr.key().asString()] = *itr;
            }
        };
    }
    void print_ent(const char* title, Json::Value value) { std::cout << title << " = " << value << std::endl; }
    void print(std::map<std::string, Json::Value*> use_map) {
        for (auto x : use_map)
            std::cout << x.first << " " << *x.second << std::endl;
    }

};
// deserialised object
class FolderArgs : public ArgsBase
{
public:
    Json::Value artifactName;   // filename .CSV
    Json::Value artifactFolder; // foldername -> CSV file
    Json::Value bitmapName;
    Json::Value bitmapFolder;

    void loadfrom(Json::Value data) { ArgsBase::loadfrom(mymap, data); }

    void print() {
        ArgsBase::print(mymap);
    }
private:
    std::map<std::string, Json::Value*> mymap{ {"artifactFolder", &this->artifactFolder},
        {"artifactName", &this->artifactName},
        {"bitmapFolder", &this->bitmapFolder},
        {"bitmapName", &this->bitmapName} };
};

/////////////////////////////////////////////////////////////////////////////////////////////////////////

int main()
{
    const std::string rawJson = R"({"bitmapName": "Bitmap Name", 
        "bitmapFolder": "Bitmap Folder",
        "artifactName": "Artifact Name",
        "artifactFolder": "Artifact Folder"})";
    const auto rawJsonLength = static_cast<int>(rawJson.length());
    JSONCPP_STRING err;
    Json::Value root;
    Json::CharReaderBuilder builder;
    const std::unique_ptr<Json::CharReader> reader(builder.newCharReader());
    if (!reader->parse(rawJson.c_str(), rawJson.c_str() + rawJsonLength, &root,
        &err)) {
        std::cout << "error: " << err << std::endl;
        return EXIT_FAILURE;
    }

    FolderArgs folders;
    folders.loadfrom(root);
    // duck type instead of using root["artifactName"]
    std::cout <<folders.artifactName << std::endl;
}

Reddit thread here https://www.reddit.com/r/cpp_questions/comments/1qkwu9s/a_reference_type_cannot_be_valueinitialized/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button