template<typename T>
typename std::enable_if<std::_Is_numeric<T>::value,T>::type
getValue()
{
    switch(_valueDataType)
    {
        case ValueDataType::BOOLEAN_TYPE:
            if (_value == "true") {
                return (T)true;
            } else {
                return (T)false;
            }
            break;
        case ValueDataType::INTEGER_TYPE:
            return (T)atoi(_value.c_str());
            break;
        case ValueDataType::DOUBLE_TYPE:
            return (T)atof(_value.c_str());
            break;
    }
    return 0;
}

string getValueAsString()
{
    return _value;
}



// Calling it

string s;
int a;
bool b;
double c;

case ValueDataType::STRING_TYPE:
    s = iter->second.getValueAsString();
    break;
case ValueDataType::INTEGER_TYPE:
    a = iter->second.getValue<int>();
    break;
case ValueDataType::BOOLEAN_TYPE:
    b = iter->second.getValue<bool>();
    break;
case ValueDataType::DOUBLE_TYPE:
    c = iter->second.getValue<double>();
    break;