withValue(_:operation:file:line:)

Declaration

@abi(nonisolated(nonsending) final func withValueNonisolatedNonsending<R>(_ valueDuringOperation: Value, operation: nonisolated(nonsending) () async throws -> R, file: String, line: UInt) async throws -> R) @discardableResult nonisolated(nonsending) final func withValue<R>(_ valueDuringOperation: Value, operation: nonisolated(nonsending) () async throws -> R, file: String = #fileID, line: UInt = #line) async rethrows -> R

Discussion

The value is available throughout the execution of the operation closure, including any get operations performed by child-tasks created during the execution of the operation closure.

If the same task-local is bound multiple times, be it in the same task, or in specific child tasks, the more specific (i.e. “deeper”) binding is returned when the value is read.

The operation is guaranteed to execute in the calling context.

If the value is a reference type, it will be retained for the duration of the operation closure.

If this method is called form a context where no current Swift concurrency task is available, a fallback thread-local is used to manage the task locals and all existing semantics of task-locals are upheld as-if a task was actually available.