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| extension Observable where Self : AnyObject, Self: Sendable { | |
| func stream<T: Sendable>(for keyPath: KeyPath<Self, T>) -> AsyncStream<T> { | |
| withObservationTrackingStream(on: self, for: keyPath) | |
| } | |
| } | |
| func withObservationTrackingStream<O, T: Sendable>( | |
| on observer: O?, | |
| for keyPath: KeyPath<O, T> | |
| ) -> AsyncStream<T> where O: AnyObject, O: Sendable { | |
| AsyncStream { [weak observer] continuation in | |
| let signal = AsyncStream<Void>.makeStream() | |
| let task = Task { @MainActor [weak observer] in | |
| defer { signal.continuation.finish() } | |
| while !Task.isCancelled { | |
| let value: (value: T, token: Void)? = withObservationTracking { | |
| guard let observer else { return nil } | |
| return (value: observer[keyPath: keyPath], token: ()) | |
| } onChange: { | |
| signal.continuation.yield(()) | |
| } | |
| guard let value else { break } | |
| continuation.yield(value.value) | |
| var iterator = signal.stream.makeAsyncIterator() | |
| guard await iterator.next() != nil else { break } | |
| } | |
| continuation.finish() | |
| } | |
| continuation.onTermination = { _ in | |
| task.cancel() | |
| } | |
| } | |
| } | |
| @Observable | |
| final class Foo { | |
| var increment: Int = 1 | |
| init() { | |
| Task { [weak self] in | |
| while !Task.isCancelled { | |
| self?.increment += 1 | |
| try? await Task.sleep(seconds: 1) | |
| } | |
| } | |
| Task { [weak self] in | |
| guard let stream = self?.stream(for: \.increment) else { return } | |
| for await value in stream { | |
| print("Incremented \(value)") | |
| } | |
| } | |
| } | |
| deinit { | |
| print("Foo Deinitialized") | |
| } | |
| } |
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