lazy-initialization

问题 I want to use Lazy initialization for some of my properties in Swift. My current code looks like this: lazy var fontSize : CGFloat = { if (someCase) { return CGFloat(30) } else { return CGFloat(17) } }() The thing is that once the fontSize is set it will NEVER change. So I wanted to do something like this: lazy let fontSize : CGFloat = { if (someCase) { return CGFloat(30) } else { return CGFloat(17) } }() Which is impossible. Only this works: let fontSize : CGFloat = { if (someCase) { return

问题 I have two business objects having many too many relationships. I am using a REST service to call the DAO method given below and get a list of political indicators for a political event. However though the piList in DAO successfully gives me the list of Political Indicators but it still gives me an exception Failed to lazily intialize a collection of role... through reference chain: org.hibernate.collection.internal.PersistentBag[0]----->PolIndicator.piList.role org.jboss.resteasy.spi

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 5 years ago . Lazy evaluation is said to be a way of delaying a process until the first time it is needed. This tends to avoid repeated evaluations and thats why I would imagine that is performing a lot faster. Functional language like Haskell (and JavaScript..?) have this functionality built

问题 Are lazy vars in Swift computed more than once? I was under the impression that they replaced the: if (instanceVariable) { return instanceVariable; } // set up variable that has not been initialized Paradigm from Objective-C (lazy instantiation). Is that what they do? Basically only called once the first time the app asks for the variable, then just returns what was calculated? Or does it get called each time like a normal computed property? The reason I ask is because I basically want a

问题 What are some recommended approaches to achieving thread-safe lazy initialization? For instance, // Not thread-safe public Foo getInstance(){ if(INSTANCE == null){ INSTANCE = new Foo(); } return INSTANCE; } 回答1: For singletons there is an elegant solution by delegating the task to the JVM code for static initialization. public class Something { private Something() { } private static class LazyHolder { public static final Something INSTANCE = new Something(); } public static Something

问题 Would like to hear experts on best practice of editing JPA entities from JSF UI. So, a couple of words about the problem. Imagine I have the persisted object MyEntity and I fetch it for editing. In DAO layer I use return em.find(MyEntity.class, id); Which returns MyEntity instance with proxies on "parent" entities - imagine one of them is MyParent . MyParent is fetched as the proxy greeting to @Access(AccessType.PROPERTY) : @Entity public class MyParent { @Id @Access(AccessType.PROPERTY)

问题 I have something that really puzzles me, specifically the following code triggers a compiler error "unresolved identifier self", and I am not sure why this is happening, as lazy means that at the time the property will be used, the class is already instantiated. Am I missing something? Many thanks in advance. Here is the code class FirstClass { unowned var second: SecondClass init(second:SecondClass) { self.second = second print("First reporting for duty") } func aMethod() { print("First's

问题 I'm working on a project using Hibernate and Jackson to serialize my objects. I think I understand how it is suposed to work but I can't manage to make it works. If I understand well, as soon as a relation fetch mode is set to LAZY, if you want this relation, you have to initialize it. Here is my class : @Entity @JsonIgnoreProperties(ignoreUnknown = true) @Table(schema="MDDI_ADMIN", name = "MINIUSINE") @Cache(usage=CacheConcurrencyStrategy.READ_WRITE) public class MiniUsine { @Id @Column(name

问题 I have some difficulties with Spring and Hibernate and lazy loading. There are a lot of questions and answers, but not really what i am looking for. So lets say i have a Car class. With an id , name and one to many relationships with doors , windows and wheels . As they are oneToMany, they are default lazy loaded which is preferred because when i want to view the name of the car i dont want to see the tires and stuff. This works in my case, using the default findOne() methods of my

问题 From what I've read so far I had the understanding that using transactions would be the solution to hibernate's lazy loading problems. The session would be available during the whole transaction in the service layer without further adue. So maybe I misconfigured my transaction management? I'm actually a newb when it comes to spring and hibernate, but maybe you guys could help me out. My configuration: <bean class="org.springframework.orm.hibernate3.LocalSessionFactoryBean" id="sessionFactory"