Error handling design: Bind error messages to error codes

Question

I have a simple structures to handle errors

enum class Error
{
    None = 0,
    FirstError,
    SecondError,
    ThirdError,
    ...
}

struct ErrorCategory
{
    static const std::string& Message(Error aError)
    {

        static const std::string messages[] =
        {
            "first error message",
            "second error message",
            "third error message",
            ...
        }

        const auto index = static_cast<size_t>(aError);
        assert(index < std::size(messages) && "Invalid error");
        return messages[index];
    }
};

Also, there are some class and methods to work with those structures.

Though it works, but the amount of errors is growing, so it becomes hard to navigate between error messages and error codes in enum. I want to declare error code and message for it in one place to make it easy to find error code. Is there a way to do it without making my code huge (such as enum + switch cases for messages) so it would be easy to maintain and without using macro?

NutCracker · Accepted Answer · 2020-03-06 13:17:19Z

1

You can use std::map<Error, std::string> like:

enum class Error : uint8_t {
    None        = 0,
    FirstError  = 1,
    SecondError = 2,
    ThirdError  = 3
};

std::map<Error, std::string> error_messages = {
    { Error::None,        "unknown error message" },
    { Error::FirstError,  "first error message"   },
    { Error::SecondError, "second error message"  },
    { Error::ThirdError,  "third error message"   }
};

and then use it afterwards like:

std::cerr << error_messages[Error::None]        << std::endl;
std::cerr << error_messages[Error::FirstError]  << std::endl;
std::cerr << error_messages[Error::SecondError] << std::endl;
std::cerr << error_messages[Error::ThirdError]  << std::endl;

Demo

answered Mar 6, 2020 at 13:17

NutCracker

12.4k5 gold badges51 silver badges74 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Cmanfred Over a year ago

Though I still have to declare enum and map, which looks quite huge for big amount of errors

NutCracker Over a year ago

@Cmanfred IMHO well if you have large amount of errors, you can't escape from writing an error message and/or error code for each of them. That's the cost you need to take.

tenfour · Accepted Answer · 2020-03-06 13:24:48Z

0

This type of operation is exactly how most localized UIs work. You map some common structured ID to a user-facing string.

Because of this, there are a huge amount of platform-specific ways of doing this which aim to do exactly what you want. For example on Windows:

(Windows) FormatMessage and Message Compiler
(Windows / .NET) .resx files and ResourceManager

answered Mar 6, 2020 at 13:24

tenfour

37k15 gold badges89 silver badges147 bronze badges

Collectives™ on Stack Overflow

Error handling design: Bind error messages to error codes

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related