Boxed creates a new BoxedKey with a default value.

NewKey creates a new Key.

WithDefault creates a new DefaultingKey with the given default value.

BoxedKey is a type that is used as a key in a context.Context that points to a handle containing the desired value.

DefaultingKey is a type that is used as a key in a context.Context for a specific type of value, but returns the default value for V if unset.

Key is a type that is used as a key in a context.Context for a specific type of value V.