https://github.com/DougGregor/swift-evolution/blob/structured-concurrency/proposals/nnnn-structured-concurrency.md#cancellation

DougGregor/swift-evolution

This maintains proposals for changes and user-visible enhancements to the Swift Programming Language. - DougGregor/swift-evolution

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func chop(_ vegetable: Vegetable) async throws -> Vegetable { await try Task.checkCancellation() // automatically throws `CancellationError` // chop chop chop ... // ... guard await !Task.isCancelled() else { print("Canceled mid-way through chopping of \(vegetable)!") throw CancellationError() } // chop some more, chop chop chop ... }

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キャンセルの取り扱いはStructured Concurrencyの方に出てきた。

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func test_cancellation_withCancellationHandler(_ anything: Any) async -> PictureData { let handle = Task.runDetached { () -> PictureData in let file = SomeFile() return await try Task.withCancellationHandler( handler: { file.close() }, operation: { await test_cancellation_guard_isCancelled(file) }) } handle.cancel() }

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https://github.com/apple/swift/pull/34459/files

9:06 AM

コールバック式のやつもPRにあった。