singleton

问题 I am using singleton pattern in an ASP.net application. I use LINQ to SQL DataContext . I face this problem: when a new record is inserted using the DataContext , it is inserted into the database when the changes are submitted. But when the same data is queried using the DataContext , the data is not retrieved, but it's read when closing and opening the application again. Please let me know how to solve this issue. I user C# 4.0, LINQ, SQL Server 2008. Regards, Jebli 回答1: An instance of

问题 I honestly think I did a pretty awesome job at creating the most exhaustive title possible :D . I have a class Db that extends MySQLi . I have some stuff going on before executing queries, but to execute a query I need to call parent::query() . The problem is that Db is singleton and I don't really know how to do that.. $result = parent::query($sql); This is what works if __construct is public. As soon as I make it private I start getting a bunch of errors basically saying Couldn't fetch db

问题 I am using Singleton in my iphone project. when I click on the sound button (I am using Singleton) for sound. when I click on the play (it will take 2 or 3 nano second) and then after the sound will play.. How can I fix this problem of sound.. 回答1: Make sure you have your audio session initialized before you play your first sound. You could do that on the - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions method. 来源： https:/

问题 I am new to OOP php , now i trying to understand the overall pattern but i struck somewhere at sharing database connection for all classes. I am referring to this answer which make db connection a singleton class and call it at each constructor. This is the singleton database class , should do the connect part and i have my autoload set class DatabaseConnection{ private static $instance; private $dbc; private function __construct(){ $this->dbc = mysqli_connect(...); } public static function

问题 Here is my singlton class using enum : public enum MyInstanceFactory { INSTANCE; private SOMEOBJECT; private int countInitialization = 0; private MyInstanceFactory(){ countInitialization++; System.out.println("WOW!! This has been initialized: ["+countInitialization+"] times"); SOMEOBJECT = SOMETHING } public Session getSomeobject(){ return SOMEOBJECT; } } Now I am calling it like inside MVC controller Session cqlSession = MyInstanceFactory.INSTANCE.getSomeobject(); In this way it calls

问题 I have a menuView in a list view controller. The menuView added on the UITableViewCell when a more button in the cell being taped. It is easy to achieve with singleton. Here is code: @implementation ProductsOperationMenu static ProductsOperationMenu *_instance; + (instancetype)sharedInstance{ static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ _instance = [[self alloc] initWithFrame:CGRectZero]; }); return _instance; } - (instancetype)initWithFrame:(CGRect)frame { if (self = [super

问题 Defining a property & synthesize for a variable in a singleton class allowed?,like below in interface, @property(nonatomic,assign)NSInteger value; and in implementation file, @synthesize value; or we just have to declare a variable like below, @interface SingletonDataClass : NSObject { NSInteger value; } 回答1: Anything that you can do with your regular classes you can do with singletons. There is no language concept called "singleton", it is just a common usage pattern of regular Objective C

问题 This is a question following by the answer from Singleton is not working in Cython The solution from the above link works when MyCythonClass do not have any attritbute to be initialize. The solution doesnt seem to be working if i have attributes to cinit my myCythonClass. I am quite new to Cython and C, any help is appreciated. cdef class Singleton: _instances = {} @classmethod def instance(cls, *args, **kwargs): if cls not in cls._instances: cls._instances[cls] = cls(*args, **kwargs) return

问题 I have a Singleton class that uses the thread-safe Singleton pattern from Jon Skeet as seen in the TekPub video. The class represents a cached list of reference data for dropdowns in an MVC 3 UI. To get the list data the class calls a static method on a static class in my DAL. Now I'm moving into testing an I want to implement an interface on my DAL class but obviously cannot because it is static and has only one static method so there's no interface to create. So I want to remove the static

问题 I do not understand why local variable is needed here: public class FinalWrapper<T> { public final T value; public FinalWrapper(T value) { this.value = value; } } public class Foo { private FinalWrapper<Helper> helperWrapper; public Helper getHelper() { FinalWrapper<Helper> tempWrapper = helperWrapper; if (tempWrapper == null) { synchronized(this) { if (helperWrapper == null) { helperWrapper = new FinalWrapper<Helper>(new Helper()); } tempWrapper = helperWrapper; } } return tempWrapper.value;