singleton

If I implement a Singleton either through holder idiom or double checked locking, but instead of calling 'getInstance()', use reflection to instantiate it, and then call 'getInstance()' on it, this would create two instances, breaking the pattern. So I add a static 'counter' member to the class, increment it in the class's private constructor, and throw an exception if it crosses '1'. But in that case, if I first instantiate through reflection, nobody else would be able to call 'getInstance()' without throwing an Exception. So how do I lazy load a Singleton yet prevent it from this attack? (I

This is my code : class SomeAudioManager: NSObject { class var sharedInstance: SomeAudioManager{ struct Static { static var onceToken: dispatch_once_t = 0 static var instance: SomeAudioManager? = nil } dispatch_once(&Static.onceToken) { Static.instance = SomeAudioManager() } return Static.instance! } func audioView(songname: NSString,format: NSString) { let audioPlayer:ava audioPlayer=try AVAudioPlayer(contentsOfURL: NSURL(fileURLWithPath: NSBundle.mainBundle().pathForResource(songname, ofType:format)!), fileTypeHint: AVFileTypeMPEGLayer3) audioPlayer!.delegate=self; self.audioPlayer!.play() }

Currently, I have a class whose constructor takes a username, password, and Context. I would like to be able to access this object from anywhere, so I was thinking of implementing a singleton pattern. The current constructor uses the credentials passed in to authenticate future api calls through that class. If I were to implement the singleton pattern, my first thought would to be have the getInstace() method take a username, password, etc.., but it seems wrong to have to pass that info everytime i grab an instance. Because of this I was thinking of adding some sort of .authenticate(usr, pswrd

In essence, what is the difference between these two classes: @ApplicationScoped @Singleton class A {} @Dependent @Singleton class B {} Contextual EJB instances I prefer not to use @Inject when looking for EJB:s, unless the EJB is a @Stateful and I want the CDI container to manage the stateful's life-cycle which could be very convenient. Otherwise, using @Inject to retrieve a contextual EJB instance is a bit dangerous. For example, a @Remote client-view cannot be retrieved using CDI unless we also write a producer . Furthermore, class A and class B can not declare any other scope than what

I'd like to start by showing a test case: class A { public static $instance=null; public function __construct(){ self::$instance=$this; } public function className(){ return get_class(self::$instance); } } class B extends A { public function className(){ return get_class(self::$instance); } } // test code $b=new B(); echo $b->className; // B $a=new A(); echo $a->className; // A echo $b->className; // A <- error: not B any more! Notes I'm using a factory+singleton patterns above. Well, somewhat. I don't need any specs on "implementing patterns correctly". I need problem solving, not KISS

i'm building a web application with asp.net c# and i have a class that i want to use in multiple pages witouth instantiate it every time. I need to load the data in it and never lose them during the user session time. I thought about the singleton-pattern but it shared the instance of the class beetween browsers. How can i solve the problem? Singleton is not the answer. Look at Session State , ViewState and Cookies . UserData data = new UserData(somedata); Session["UserData"] = data; next page UserData data = (UserData) Session["UserData"]; If you have inproc session state you can use