Protocols

BaggageKeys are used as keys in a Baggage. Their associated type Value guarantees type-safety. To give your BaggageKey an explicit name you may override the name property.

In general, BaggageKeys should be internal or private to the part of a system using it.

All access to baggage items should be performed through an accessor computed property defined as shown below:

/// The Key type should be internal (or private).
enum TestIDKey: Baggage.Key {
    typealias Value = String
    static var nameOverride: String? { "test-id" }
}

extension Baggage {
    /// This is some useful property documentation.
    public internal(set) var testID: String? {
        get {
            self[TestIDKey.self]
        }
        set {
            self[TestIDKey.self] = newValue
        }
    }
}

This pattern allows library authors fine-grained control over which values may be set, and whic only get by end-users.

See more

public protocol BaggageKey