Merge pull request #49 from RxSwiftCommunity/feature/hasDisposeBag

feature: rehabilitates the HasDisposeBag protocol

Demo/DemoTests/DemoTests.swift

@@ -3,31 +3,48 @@ import Nimble
 import RxSwift
 import NSObject_Rx
 
+class DisposeBagTest: HasDisposeBag {
+
+}
+
 class Test: QuickSpec {
     override func spec() {
         it("respects setter") {
             var subject = NSObject()
             let disposeBag = DisposeBag()
             subject.rx.disposeBag = disposeBag
-
+            let subjectProtocol = DisposeBagTest()
+            subjectProtocol.disposeBag = disposeBag
             expect(subject.rx.disposeBag) === disposeBag
+            expect(subjectProtocol.disposeBag) === disposeBag
         }
 
         it("diposes when object is deallocated") {
             var executed = false
+            var executedProtocol = false
+
             let variable = PublishSubject<Int>()
+            let variableProtocol = PublishSubject<Int>()
 
             // Force the bag to deinit (and dispose itself).
             do {
                 let subject = NSObject()
+                let subjectProtocol = DisposeBagTest()
+
                 variable.subscribe(onNext: { _ in
                     executed = true
                 }).addDisposableTo(subject.rx.disposeBag)
+
+                variableProtocol.subscribe(onNext: { _ in
+                    executedProtocol = true
+                }).addDisposableTo(subjectProtocol.disposeBag)
             }
 
             // Force a new value through the subscription to test its been disposed of.
             variable.onNext(1)
+            variableProtocol.onNext(1)
             expect(executed) == false
+            expect(executedProtocol) == false
         }
 
         it("disposes using rx.disposeBag") {

HasDisposeBag.swift

@@ -0,0 +1,44 @@
+import Foundation
+import RxSwift
+import ObjectiveC
+
+fileprivate var disposeBagContext: UInt8 = 0
+
+/// each HasDisposeBag offers a unique RxSwift DisposeBag instance
+public protocol HasDisposeBag: class {
+
+    /// a unique RxSwift DisposeBag instance
+    var disposeBag: DisposeBag { get set }
+}
+
+extension HasDisposeBag {
+
+    func synchronizedBag<T>( _ action: () -> T) -> T {
+        objc_sync_enter(self)
+        let result = action()
+        objc_sync_exit(self)
+        return result
+    }
+
+    public var disposeBag: DisposeBag {
+        get {
+            return synchronizedBag {
+                if let disposeObject = objc_getAssociatedObject(self, &disposeBagContext) as? DisposeBag {
+                    return disposeObject
+                }
+                let disposeObject = DisposeBag()
+                objc_setAssociatedObject(self, &disposeBagContext, disposeObject, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
+                return disposeObject
+            }
+        }
+
+        set {
+            synchronizedBag {
+                objc_setAssociatedObject(self, &disposeBagContext, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
+            }
+        }
+    }
+}
+
+
+