singleton

Switching between singleton and prototype scope using RequireJS

由 自古美人都是妖i 提交于 2019-12-08 07:51:27
问题 Spring has very useful option, that whey I define a bean, I define a scope. If it's singleton , only one instance is created. By prototype , each time a bean is required, a new instance is created. RequireJS provides by default singletons, so with such simple module: Singleton.js define([], function() { console.log('Instance initialization') var items = [] var singleton = { getItems: function() { return items }, setItems: function(newItems) { items = newItems }, addItem: function(item) {

Can i make my own Singleton Stateless Bean with EJB 3.0?

由 家住魔仙堡 提交于 2019-12-08 07:51:09
问题 Now, with EJB 3.1, we can find the javax.ejb.Singleton annocation that can ensure that this bean is going to be singleton. Is there a way that i can ensure singleton using stateless beans in EJB 3.0 with some modifications in my code (use of the keyword static, or other way to do that....) 回答1: If you're able to limit your @Stateless bean pool size to exactly 1, then you can get pretty close to an @Singleton . The effect would be like having an @Singleton that uses @Lock(WRITE) for all calls

Connection Manager: Singleton or not Singleton?

由 断了今生、忘了曾经 提交于 2019-12-08 07:48:41
问题 My iOS app does a lot of different requests to a Web service. Each request is a call to a method of a ConnectionManager object. When the response arrives from the Web service, a delegate's method is called to notify an interested receiver. Moreover, to maintain the session active, a polling every X seconds is required. Said so, in your opinion it is better if ConnectionManager is a Singleton or not? The singleton is simpler (because I do not have to pass a ConnectionManager's reference to all

which scope should a DAO typically have

由 爱⌒轻易说出口 提交于 2019-12-08 07:44:53
问题 its out of question that a dao will not hold any state. however, for easiest access to the class, is it better to use prototype( = new every time) or singleton? simple object creation is cheap for dao's.. it typically only holds a sessionfactory, accessing the object from a list of singletons may be equally expensive. clarfication: the focus of this question is, if there is a common convention to the scoping of daos. 回答1: If your question is about architecture , I'd go with scoping DAOs to

PDO with Singleton cannot access private property

由 馋奶兔 提交于 2019-12-08 07:20:53
问题 I´ve made a database connection with PDO and the singleton pattern. Everything works fine as long as I have the $_db variable set as public but it needs to be private... When I make it private I off course get the Error: Cannot access private property Database::$_db Can someone tell me how to make it private and still be able to get an instance? When I call the database connection from another file I call the function getInstance() Here is an example how I call it from one file: $db =

Using Singleton vs Single Call in .NET Remoting?

由 被刻印的时光 ゝ 提交于 2019-12-08 07:01:11
问题 Up until this point all the .NET remoting code I have written or worked with has been exposed as SingleCall. I ran across a .NET remoting component hosted in a Windows service that is exposed as a Singleton. This object has the potential to be called by more than one client at the same time, and it has no locks or other provisions to protect its internal state. If I understand Singleton correctly then this has the potential for big problems correct? 回答1: No more potential than a SingleCall

How to make a single shared instance of iAd banner throughout many view controllers?

由 最后都变了- 提交于 2019-12-08 07:00:55
问题 I have tried using a singleton class in my app delegate but I haven't been able to get that to work. I've also checked out the iAdSuite examples (particularly the containerBanner example because it seemed to be the most relative) but I can't figure it out. If there's a better way to accomplish this without using a singleton class and you can point me in the right direction I'd really appreciate it. Some of my singleton class code is below. Thank you! @interface App Delegate @property (assign)

meaning and location of string inside Magento's Mage:getSingleton

由 好久不见. 提交于 2019-12-08 06:48:00
问题 Here is a string I see a lot of similar in Magento: Mage::getSingleton('checkout/type_onepage'); However, I'm trying to find out where that class is located, and what the meaning of the string is specifically. Can anyone explain this to me? 回答1: 1/ Model You have to know that Mage::getSingleton() is going to send you a singleton (which is a common development design pattern). For magento, only Models can be instantiated as a Singleton Snippet from app/Mage.php where you can see that Magento

Thread safety of method calls on “shared” static constant property

由 邮差的信 提交于 2019-12-08 06:43:20
I have a Swift class which uses a traditional Cocoa singleton pattern: one static shared constant and a private init that is only called once for that shared constant. It's like this: public class Foo { public static let shared = Foo() private init() { /* ... */ } public func bar() { /* ... */ } public func baz() { /* ... */ } } // Meanwhile, in multiple places upon multiple threads: Foo.shared.bar() Foo.shared.baz() If I have a dozen threads calling functions on that constant, does it pause all calls until that initializer completes, or should I have some protections within those instance

can some one confirm if this is a thread safe implementation of singleton

由 帅比萌擦擦* 提交于 2019-12-08 06:42:58
问题 #include "iostream" #include "atomic" using namespace std; class Singleton { Singleton(); static Singleton * _pInstance; public: ~Singleton() { } static Singleton* getInstance() { Singleton * tmp = _pInstance; atomic_thread_fence(std::memory_order_acquire); if (tmp == nullptr){ tmp = _pInstance; if (!tmp) { _pInstance = new Singleton(); atomic_thread_fence(std::memory_order_release); _pInstance = tmp; } return _pInstance; } }; Singleton* Singleton::_pInstance = nullptr; 回答1: Your
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