Modern Error Handling

Use optional, variant, expected, exceptions, and result-oriented APIs deliberately.

Modern Error Handling

Choose the right tool

Use exceptions for exceptional failures that should cross multiple layers.
Use std::optional<T> when absence is normal and there is no extra error detail.
Use std::expected<T, E> when callers should handle a typed error locally.
Use std::variant<Ts...> when a result can be one of several valid shapes.

std::optional<int> find_id(std::string_view name);

if (auto id = find_id("ada")) {
    std::cout << *id << '\n';
}

Use it for "maybe there is a value". Do not overload it with detailed failure reasons.

enum class ParseError { invalid_digit, overflow };

std::expected<int, ParseError> parse_port(std::string_view text);

std::expected keeps the success path explicit and makes error propagation testable.

using ConfigValue = std::variant<int, bool, std::string>;

Visit a variant when the set of alternatives is fixed and meaningful.