EDIT : The implementation of a Singleton in Android is not “safe” (see here) and you should use a library dedicated to this kind of pattern like Dagger or other DI library to manage the lifecycle and the injection. Could you post an example from your code ? Take a look at this gist : https://gist.github.com/Akayh/5566992 it works … Read more
On my quest for the truth I discovered that there are actually very few “acceptable” reasons to use a Singleton. One reason that tends to come up over and over again on the internets is that of a “logging” class (which you mentioned). In this case, a Singleton can be used instead of a single … Read more
I think the easiest way is to declare a simple object literal: If you want private members on your singleton instance, you can do something like this: This has been called the module pattern, and it basically allows you to encapsulate private members on an object, by taking advantage of the use of closures. If … Read more
Spring’s default scope is singleton. It’s just that your idea of what it means to be a singleton doesn’t match how Spring defines singletons. If you tell Spring to make two separate beans with different ids and the same class, then you get two separate beans, each with singleton scope. All singleton scope means is that when … Read more
What makes you say that either a singleton or a static method isn’t thread-safe? Usually both should be implemented to be thread-safe. The big difference between a singleton and a bunch of static methods is that singletons can implement interfaces (or derive from useful base classes, although that’s less common, in my experience), so you can pass … Read more
First, the class << foo syntax opens up foo‘s singleton class (eigenclass). This allows you to specialise the behaviour of methods called on that specific object. Now, to answer the question: class << self opens up self‘s singleton class, so that methods can be redefined for the current self object (which inside a class or module body is the class or module itself). Usually, … Read more
In 2008 I provided a C++98 implementation of the Singleton design pattern that is lazy-evaluated, guaranteed-destruction, not-technically-thread-safe:Can any one provide me a sample of Singleton in c++? Here is an updated C++11 implementation of the Singleton design pattern that is lazy-evaluated, correctly-destroyed, and thread-safe. See this article about when to use a singleton: (not often)Singleton: How … Read more
In 2008 I provided a C++98 implementation of the Singleton design pattern that is lazy-evaluated, guaranteed-destruction, not-technically-thread-safe:Can any one provide me a sample of Singleton in c++? Here is an updated C++11 implementation of the Singleton design pattern that is lazy-evaluated, correctly-destroyed, and thread-safe. See this article about when to use a singleton: (not often)Singleton: … Read more
I don’t really see the need, as a module with functions (and not a class) would serve well as a singleton. All its variables would be bound to the module, which could not be instantiated repeatedly anyway. If you do wish to use a class, there is no way of creating private classes or private … Read more
A singleton is a class which only allows one instance of itself to be created – and gives simple, easy access to said instance. The singleton premise is a pattern across software development. There is a C# implementation “Implementing the Singleton Pattern in C#” covering most of what you need to know – including some … Read more