singleton

问题 In my rails app I've decided to use singleton to create some sort of factory to get objects properly. config/initializers/registry.rb: registry = Registry.instance registry.define_lazy :period_predictor do PeriodPredictor.new(NotificationBuilder.new, 28, 4, 3) end registry.define_lazy :notification_sender do NotificationSender.new end lib/registry.rb: # Registry class which is singleton and stores values. class Registry include Singleton # Define simple value. Like a constant. # # @param key

问题 I have a Python 3 class that is currently a singleton defined using a @singleton decorator, but occasionally it needs to not be a singleton. Question: Is it possible to do something similar to passing a parameter when instantiating an object from the class and this parameter determines whether the class is a singleton or not a singleton? I am trying to find an alternative to duplicating the class and making that not a singleton, but then we will have tons of duplicated code. Foo.py def

问题 Is there any difference between a Singleton class and a class with all static members (i.e. methods and attributes). I could not find any instance where 'all static member class' would not achieve the same functionality as class properly implementing Singleton pattern? For eg. java.lang.Runtime is a proper Singleton class whereas java.lang.System has all static method for access and merely has a private constructor to avoid external construction . Does anybody know why classes like Runtime

问题 Is there any difference between a Singleton class and a class with all static members (i.e. methods and attributes). I could not find any instance where 'all static member class' would not achieve the same functionality as class properly implementing Singleton pattern? For eg. java.lang.Runtime is a proper Singleton class whereas java.lang.System has all static method for access and merely has a private constructor to avoid external construction . Does anybody know why classes like Runtime

问题 Is there any difference between a Singleton class and a class with all static members (i.e. methods and attributes). I could not find any instance where 'all static member class' would not achieve the same functionality as class properly implementing Singleton pattern? For eg. java.lang.Runtime is a proper Singleton class whereas java.lang.System has all static method for access and merely has a private constructor to avoid external construction . Does anybody know why classes like Runtime

问题 In dll A I have a template singleton: template <class T> class Singleton { public: static T &instance() { static T _instance; return _instance; } private: //All constructors are here }; In Dll B I define a class Logger. Dlls C,D and E use the Logger and it is accessed like this: Singleton<Logger>::instance(); The problem is that each dll instantiates its own copy of Singleton<Logger>. instead of using the same singleton instance. I understand that the solution to this problem is using extern

问题 In dll A I have a template singleton: template <class T> class Singleton { public: static T &instance() { static T _instance; return _instance; } private: //All constructors are here }; In Dll B I define a class Logger. Dlls C,D and E use the Logger and it is accessed like this: Singleton<Logger>::instance(); The problem is that each dll instantiates its own copy of Singleton<Logger>. instead of using the same singleton instance. I understand that the solution to this problem is using extern

问题 I have an example code like this: public class SimpleLogger { private static SimpleLogger logger; private string path = null; protected SimpleLogger(string path) { this.path = path; } public static SimpleLogger Instance(string path) { if (logger == null) { logger = new SimpleLogger(path); } return logger; } public static void Info(string info) { string path = $"{logger.path}{DateTime.Now.ToShortDateString()}_Info.txt"; using (StreamWriter writer = new StreamWriter(path)) { writer.WriteLine($"

问题 I'm declaring a Singleton class where I need to pass context parameter for one of the methods in this class public class MySingleton() { Private Context mContext; Private static MySingleton mInstance; public static MySingleton mInstance() { if (mInstance == null) { mInstance = new MySingleton(); } return mInstance; } public void myMethod(Context context) { this.mContext = context; // write your code here.... } } will this cause a memory leak. 回答1: It could, as you do not know what sort of

问题 Is there a way in Unity3d framework to register an object that would be accessible to all entities in all scenes in the game without resorting to singleton pattern (like a game state object)? 回答1: You could take the following approach: In the scene where the GameObject is created, in a MonoBehavior script attached to the GameObject: Name the GameObject with "name = ..." in Awake() (or in the Editor) Example: myObject.name = "FindMeInEveryScene"; Ref: https://docs.unity3d.com/ScriptReference