subclassing

What is the easiest way to create my own std::cerr so that it is line-by-line thread-safe. I am preferably looking for the code to do it. What I need is so that a line of output (terminated with std::endl ) generated by one thread stays as a line of output when I actually see it on my console (and is not mixed with some other thread's output). Solution : std::cerr is much slower than cstdio. I prefer using fprintf(stderr, "The message") inside of a CriticalSectionLocker class whose constructor acquires a thread-safe lock and the destructor releases it. If available, osyncstream (C++20) solves

Why doesn't Swift allow me to assign value Foo<U> to a variable of type Foo<T> , where U is a subclass of T? For example: class Cheese { let smell: Int let hardness: Int let name: String init(smell: Int, hardness: Int, name: String) { self.smell = smell self.hardness = hardness self.name = name } func cut() { print("Peeyoo!") } } class Gouda: Cheese { let aged: Bool init(smell: Int, hardness: Int, name: String, aged: Bool) { self.aged = aged super.init(smell: smell, hardness: hardness, name: name) } override func cut() { print("Smells delicious") } } class Platter<Food> { var food: Food init

I've been attempting to follow a tutorial about creating a container view controller. It's in Objective-C. I want to convert it to Swift. I've found some of the same questions here, but I didn't get too much out of them. Here's the code. import UIKit class ContainerViewController: UIViewController { // Class "ContainerViewController" has no initializers - That I know why. // 'required' initializer 'init(coder:)' must be provided by a subclass of UIViewController var currentDetailViewController: UIViewController override func viewDidLoad() { super.viewDidLoad() } override func

I am new to java and I am trying to create an XML document and clone a specific node (minus the textnode) of this document over and over again. Someone answered me and said that I should subclass the node and override the cloning. So my question is what is sub-classing? @Charlie Martin has explained what subclassing means. However, it is not clear that you've been given good advice. If you are creating the XML document by assembling a DOM in memory, a better approach would be to create a helper class with static methods that perform the sequence of DOM node operations that you need to do.

I would like to be able to thin the UITabBar's height by removing each item's titles and reclaiming the vertical space they take up, a la Tweetie 2. This doesn't seem settable in the .xib or programmatically. Will I have to subclass the UITabBar and roll my own? Roll your own. I'm sure Tweetie 2's is custom; and the height is set in the handed down UITabBar. You can achieve a similar effect by placing a segmented control inside a uitoolbar. I did this and it looks quite nice. 来源： https://stackoverflow.com/questions/1563701/making-a-thinner-uitabbar