How do I serialize and deserialize std::expected (when available) in C++?

Serialization and deserialization of C++ types are crucial for various applications, especially when it comes to data storage or network communication. With the introduction of `std::expected` in C++20, it allows you to convey expected and unexpected outcomes in a more structured way. This post explains how to serialize and deserialize `std::expected` objects.

Keywords: C++, std::expected, serialization, deserialization, C++20
Description: This article discusses the serialization and deserialization methods for `std::expected` in C++20, providing code examples for better understanding.

Serialization of std::expected

To serialize an `std::expected`, we can convert it to a JSON-like format or any string representation that suits our needs. Here is a simple example using a hypothetical function that converts our expected object to a string.

#include #include #include // Example of a serialization function template std::string serialize(const std::expected& ex) { if (ex.has_value()) { return "Value: " + std::to_string(ex.value()); } else { return "Error: " + std::to_string(ex.error()); } }

Deserialization of std::expected

To deserialize, we will parse the string representation back into an `std::expected` object.

// Example of a deserialization function template std::expected deserialize(const std::string& str) { // A simple mock-up to demonstrate the concept if (str.rfind("Value:", 0) == 0) { T value = std::stod(str.substr(6)); // Assumes T can be initialized from string return std::expected(value); } else { E error = static_cast(std::stoi(str.substr(7))); // Assumes E is integer for simplicity return std::unexpected(error); } }

This approach gives you a straightforward way to serialize and deserialize `std::expected` instances. Adjust the serialization logic as needed based on the types you're working with, including custom objects.


Keywords: C++ std::expected serialization deserialization C++20

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