@swift-6.2
import Synchronization @MainActor final class SomeProxy { func foo() {} func bar() {} } struct SomeProxyClient { var setProxy: @Sendable (SomeProxy) -> Void var foo: @MainActor @Sendable () -> Void var bar: @MainActor @Sendable () -> Void static let liveValue: Self = { let _proxy = Mutex<SomeProxy?>(nil) return Self( setProxy: { proxy in _proxy.withLock { $0 = proxy } }, foo: { guard let proxy = _proxy.withLock(\.self) else { fatalError("proxy must not be nil.") } proxy.foo() }, bar: { guard let proxy = _proxy.withLock(\.self) else { fatalError("proxy must not be nil.") } proxy.bar() } ) }() }