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omochimetaru 2/15/2018 10:22 AM
public func once<T, R>(_ f: @escaping (T) -> R) -> (T) -> R { var done: Bool = false return { (t: T) -> R in guard !done else { fatalError("do not twice") } done = true return f(t) } } public class Cat { public init(name: String) { self.name = name self.onBorn() } public var name: String public func onBorn() { _onBorn(self) } private let _onBorn: (Cat) -> Void = once { `self` in print("\(self.name)がうまれた") } } Cat(name: "tama")
10:23 AM
onBorn を let にしたかったけど self がキャプチャできなかったので func onBorn と let _onBorn に分かれてしまう。
10:25 AM
public class Cat { public init(name: String) { self.name = name self.onBorn() } public var name: String public lazy var onBorn: () -> Void = once { [unowned self] in print("\(self.name)がうまれた") } }
10:27 AM
lazyだと使えるのか。でもこれじゃ駄目だなあ