C++ enums with attributes like C# - c++

Question

I have the following C# Code which I need to convert into C++ code. I have searched for a bit on how to do C++ Enums with Attributes and can not figure it out.
Basically I need a way to represent the following simplified C# Code in C++ which would do enums with attributes.
C# Code:
public class PSMNameAttribute : Attribute
{
public string PSMName;
public PSMNameAttribute(string _PSMName) { PSMName = _PSMName; }
}
public class PSMNumberAttribute : Attribute
{
public string PSMNumber;
public PSMNumberAttribute(string _PSMNumber) { PSMNumber = _PSMNumber; }
}
public class PSMNumberNameAttribute : Attribute
{
public string PSMNumberName;
public PSMNumberNameAttribute(string _PSMNumberName) { PSMNumberName = _PSMNumberName; }
}
public enum ShippingMethodsTypes
{
[PSMName("ErrorScriptMed")]
[PSMNumber("-5")]
[PSMNumberName("-5 ErrorScriptMed")]
ErrorScriptMed = -5
,
[PSMName("SpecialHandling")]
[PSMNumber("-1")]
[PSMNumberName("-1 SpecialHandling")]
SpecialHandling = -1
,
[PSMName("Error")]
[PSMNumber("0")]
[PSMNumberName("0 Error")]
Error = 0
}
Could this be done like this:
enum Category{
unknown = -1, meat, poultry, seafood, dairy, vegetable,fruit, grain, sweet
};
typedef struct {
float calories; // calories
float carbonhydrates; // grams
float fat; // grams
float cholesterol; // grams
float sodium; // grams
float protein; // grams
Category category ;
}Food;
and if so how would I call the struct values using the enum?

Answer 1

boost::variant and a few visitors should solve it nicely:
#include <boost/variant.hpp>
#include <iostream>
struct get_number : boost::static_visitor<int> {
template<class Method> int operator()(const Method& m) const { return number(m); }
};
struct get_name : boost::static_visitor<std::string> {
template<class Method> const std::string operator()(const Method& m) const { return name(m); }
};
struct ShippingMethodMed {};
static constexpr int number(ShippingMethodMed) { return -5; }
static std::string name(ShippingMethodMed) { return "ErrorScriptMedMed"; }
struct ShippingMethodSpecialHandling { };
static constexpr int number(ShippingMethodSpecialHandling) { return -10; }
static std::string name(ShippingMethodSpecialHandling) { return "SpecialHandling"; }
struct ShippingMethodError {};
static constexpr int number(ShippingMethodError) { return 0; }
static std::string name(ShippingMethodError) { return "Error"; }
using ShippingMethod = boost::variant<ShippingMethodMed, ShippingMethodSpecialHandling, ShippingMethodError>;
int number(ShippingMethod const& sm) {
return boost::apply_visitor(get_number(), sm);
}
std::string name(ShippingMethod const& sm) {
return boost::apply_visitor(get_name(), sm);
}
std::string number_name(ShippingMethod const& sm) {
return std::to_string(number(sm)) + " " + name(sm);
}
int main()
{
ShippingMethod m = ShippingMethodError();
std::cout << number(m) << std::endl;
std::cout << name(m) << std::endl;
std::cout << number_name(m) << std::endl;
m = ShippingMethodSpecialHandling();
std::cout << number(m) << std::endl;
std::cout << name(m) << std::endl;
std::cout << number_name(m) << std::endl;
}

Answer 2

This is not possible with enums alone.
However I think you could solve this by maintaining a string array/vector/map or a combination of those to your enum like:
enum test
{
first = 0,
second, // = 1
// etc...
};
const char* attributes[] =
{
"first attribute",
"second attribute",
};
then you could retrieve this attribute through
const char* firstattribute = attributes[test::first];