class-extensions

问题 Is there anyhow anyway to add some static method to types like Date , String , Array , etc? For example I want to add method today to Date class and in JavaScript I can simply add a property to it or maybe I use Object.defineProperty: Date.today = function(){ let date = new Date; date.setHours(0,0,0,0); return date; } Object.defineProperty(Date, 'today', { get() { ... }}); But I didn't find anyway to inform TypeScript about this new static member. Am I missing something or Did I google it the

问题 I'm slowly building my personal website over at dlblack.dev, and I'm trying to spice it up a little bit. For example, from a computer (rather than a tablet or phone since they don't have mouse pointers), if you hover over any of the clickable items, it doesn't change your mouse pointer to indicate it's clickable, and the clickable object doesn't change at all. I've decided to follow this FilledStacks tutorial, but it doesn't mention anything about fixing this problem. Essentially what's

问题 Sorry for my English, let speak from my heart :) In one project which I work, I noticed an interesting moment. In *.h file declared interface: @interface FrontViewController : UIViewController ... @end And in *.m file I found another interface. @interface FrontViewController() // Private Properties: @property (retain, nonatomic) UIPanGestureRecognizer *navigationBarPanGestureRecognizer; // Private Methods: - (IBAction)pushExample:(id)sender; @end @implementation FrontViewController ... @end

问题 I want to extend core Array class with simple method: class Array def to_hash result = Hash.new self.each { |a| result[a] = '' } result end end I put array.rb into lib/core_ext and tried to require it in application.rb by config.autoload_paths += %W(#{config.root}/lib) config.autoload_paths += Dir["#{config.root}/lib/**/"] But still get undefined method 'to_hash' for ["var1", "var2", "var3"]:Array if tried to use it in model method. Of course I rebooted the server after code changes. 回答1:

问题 There are several situations where you might override a super class's property. You declare a property with the same name and same attribute of its superclass'.(since if you change the attribute you can get an compiler warning).And you can synthesieze with an ivar that you create. What's the use of this? Or what's the harm can it do? If a superclass declares a property in a class extension (a category with no name), then it might not be in the header file. If you don't know that property from

问题 I believe a popular way to declare "private methods" in Objective-C is to create its class extension and declare methods that you would like to make as private. I would like to know more in detail on how an class extension makes the methods work as private. Update: I asked this question with the term empty category which is incorrect. I now changed it as class extension 回答1: That's not an "empty category", it's a class extension. Read Bbum's explanation of them at the link I provided. 回答2:

问题 I don't understand why programmers use the extension keyword in their class implementation. You can read in other topics that code is then more semantically separated and etc. But when I work with my own code, it feels clearer to me to use // MARK - Something . Then when you use methods list (ctrl+6) in Xcode, everything is seen at first look. In Apple documentation you can read: “Extensions add new functionality to an existing class, structure, or enumeration type.” So why not write my own

问题 I feel this is a basic question wiht some trick. I want to extend the functionality of ActionBar, upon looking up the ActionBar code it turns out ActionBar is an abstract class and the real instantiated class is ActionBarImpl. This pattern of having an abstract and a Impl for implementation is widely used in android source code. The developers site does not dwell in details, but always describes the abstract class as if it was the implemented class. I see that from the java language strict

问题 I'm working on exercise 3 on page 76 in Apple's developer pdf in the class categories and extensions section, "Programming with Objective C", found here: (https://developer.apple.com/library/mac/documentation/cocoa/conceptual/ProgrammingWithObjectiveC/Introduction/Introduction.html) my XYZPerson header looks like this: #import <Foundation/Foundation.h> @interface XYZPerson : NSObject @property (readonly) NSNumber *height; @property (readonly) NSNumber *weight; -(NSNumber *)measureHeight; -

问题 This question already has answers here : Objective-C class extension (5 answers) Closed 6 years ago . What exactly are class extensions and header files? What are the differences? What is the difference between declaring a property/method in a header file vs in a class extension. I am completely new to objective-c so beginner terminology would be beneficial :) Thanks in advance! 回答1: As the name suggests, they extend the class. A class continuation is another name. The class extension is