computed-properties

I have a component with the following hash { computed: { isUserID: { get: function(){ return this.userId? } } } Should I be watching isUserID or userId for changes? Can you watch computed properties? Saurabh Yes, you can setup watcher on computed property, see the fiddle . Following is the code to set watch on computed property: const demo = new Vue({ el: '#demo', data() { return { age: '' }; }, computed: { doubleAge() { return 2 * this.age; } }, watch: { doubleAge(newValue) { alert(`yes, computed property changed: ${newValue}`); } } }); David William computed: { name: { get: function(){

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 computed property in Swift that can access other instance variables. Say I have a variable called "fullName

I'm new to Swift. What is the difference between a computed property and a property set to a closure? I know a computed property gets recalculated each time. Is it different for the closure? i.e. Closure: var pushBehavior: UIPushBehavior = { let lazilyCreatedPush = UIPushBehavior() lazilyCreatedPush.setAngle(50, magnitude: 50) return lazilyCreatedPush }() Computed: var pushBehavior: UIPushBehavior { get{ let lazilyCreatedPush = UIPushBehavior() lazilyCreatedPush.setAngle(50, magnitude: 50) return lazilyCreatedPush } } The first is a stored property that is initialized via a closure. The second

How can I use computed property in lists. I am using VueJS v2.0.2. Here's the HTML: <div id="el"> <p v-for="item in items"> <span>{{fullName}}</span> </p> </div> Here's the Vue code: var items = [ { id:1, firstname:'John', lastname: 'Doe' }, { id:2, firstname:'Martin', lastname: 'Bust' } ]; var vm = new Vue({ el: '#el', data: { items: items }, computed: { fullName: function(item) { return item.firstname + ' ' + item.lastname; }, }, }); You can't create a computed property for each iteration. Ideally, each of those items would be their own component so each one can have its own fullName

I have the following class: class ReportView: NSView { var categoriesPerPage = [[Int]]() var numPages: Int = { return categoriesPerPage.count } } Compilation fails with the message: Instance member 'categoriesPerPage' cannot be used on type 'ReportView' What does this mean? Daniel Krom You just have syntax error when saying = {return self.someValue} . The = isn't needed. Use : var numPages: Int { get{ return categoriesPerPage.count } } if you want get only you can write var numPages: Int { return categoriesPerPage.count } with the first way you can also add observers as set willSet & didSet

What is the main difference between a method and a computed value in Vue.js? They look the same and interchangeable. Computed values and methods are very different in Vue and are definitely not interchangeable in most cases. Computed Property A more appropriate name for a computed value is a computed property . In fact, when the Vue is instantiated, computed properties are converted into a property of the Vue with a getter and sometimes a setter. Basically you can think of a computed value as a derived value that will be automatically updated whenever one of the underlying values used to