singleton

问题 I have an AIR application that uses Singletons to manage global state throughout the application. Works great for what it does (manages a network appliance). But now the client wants to spawn multiple application instances from the first instance so they can manage multiple hardware devices at the same time ... kind of like a dashboard but lots bigger. As you can guess, I coded myself into a corner with the singletons so if I refactor the application to have a bootstrap class that launches

问题 I have an AIR application that uses Singletons to manage global state throughout the application. Works great for what it does (manages a network appliance). But now the client wants to spawn multiple application instances from the first instance so they can manage multiple hardware devices at the same time ... kind of like a dashboard but lots bigger. As you can guess, I coded myself into a corner with the singletons so if I refactor the application to have a bootstrap class that launches

问题 Read this first pls: does __init__ get called multiple times with this implementation of Singleton? (Python) class Singleton(object): _instance = None def __new__(cls, *args, **kwargs): print 'Singleton.__new__ called with class', cls if not cls._instance: print 'Singleton.__new__ creating instance of class', cls cls._instance = super(Singleton, cls).__new__(cls, *args, **kwargs) cls._instance.__init__(*args, **kwargs) class Cache(Singleton): def __init__(self, size=100): print 'Cache.__init_

问题 We have a backend application with Spring IOC with Jersey REST. All the spring beans we define use default scope, I mean, singleton. This application is DB-centric with huge number of users. My question: how spring singleton beans manage the concurrency over this application? None of the methods in service classes are defined as synchronized, but we never get any issues with user data synchronization. Everything looks perfectly OK. I think I am missing something about the spring singleton

问题 I have a template singleton class, with a static instance, and a static getInstance() method. However, I'm getting an undefined reference error on the instance from g++ (MinGW); at first, I thought it was linker-order error, but I get the same thing no matter which order I put them in. However, I found that if I explicitly specialize the instance, it does compile (which isn't an acceptable solution). So, here's the code: Singleton.hpp: #ifndef SINGLETON_HPP #define SINGLETON_HPP #include

问题 Still struggling with this.types (singleton types). Assume this scenario: trait Sys[A <: Access] { def in[T](v: String): AccessPrepare[A] } trait AccessPrepare[A <: Access] { val a: A def apply[T](fun: a.type => T): T } object Ref { def single[A <: Access, V](v: V)(implicit a: A): Ref[A, V] = ??? } trait Ref[A, V] trait Access { def set(r: Ref[this.type, Int]): Unit } The following fails: def test(sys: Sys[Access]): Unit = sys.in("v1") { implicit a => val r = Ref.single(44) a.set(r) } because

问题 Still struggling with this.types (singleton types). Assume this scenario: trait Sys[A <: Access] { def in[T](v: String): AccessPrepare[A] } trait AccessPrepare[A <: Access] { val a: A def apply[T](fun: a.type => T): T } object Ref { def single[A <: Access, V](v: V)(implicit a: A): Ref[A, V] = ??? } trait Ref[A, V] trait Access { def set(r: Ref[this.type, Int]): Unit } The following fails: def test(sys: Sys[Access]): Unit = sys.in("v1") { implicit a => val r = Ref.single(44) a.set(r) } because

问题 I have a piece of code like below and it works perfectly fine but PHP Storm doesn't show code completion and I am unable to CTRL+click to open the method. Is there a way to make PHP storm aware of the method's location for quicker opening? $data= MyCoolBusinessManager::Instance()->GetSomeData(); Just an FYI, I am also making use of the spl_autoload_register() function instead of having includes all over the place since my classes follow a standard naming format. 回答1: You need to put a PHPDoc

问题 If you have a Java Singleton that looks like this: public class MySingleton { private static MySingleton instance; private int member; public static MySingleton getInstance(){ if(instance==null){ instance = new MySingleton(); } return instance; } private MySingleton(){ //empty private constructor } public int getMemberA(){ return member; } public int getMemberB(){ return instance.member; } } ...is there a difference between getMemberA and getMemberB? That is, is there a difference between

问题 I have a log4net wrapper class... But i need to instantiate everytime when i call it from other classes to log the error. I need to overcome that.. Recently i came across the singleton class which is not familiar to me.. Hence I need help in converting my current wrapper class to the singleton class.. I am posting my log4net wrapper class which i am currently using below.. using System; using System.Data; using System.Configuration; using Asset.Business; /// <summary> /// Summary description