Using用法

class DisposableResource: Disposable {
    var values: [Int]
    func dispose() {
        self.values = []
    }
    init(_ values: [Int]) {
        self.values = values
    }
}

let observable = Observable<Int>.using({ () -> DisposableResource in
    return DisposableResource([1, 2, 3])
}, observableFactory: { (resource) -> Observable<Int> in
    return Observable<Int>.from(resource.values)
})

observable.debug().subscribe().disposed(by: bag)
// subscribed
// Event next(1)
// Event next(2)
// Event next(3)
// Event completed
// isDisposed