closures

问题 I see in the docs and in Closure.java references to "directive" with no explanation of whgat it is or what it is for, public static final int DONE = 1, SKIP = 2; private int directive; /** * @return Returns the directive. */ public int getDirective() { return directive; } /** * @param directive The directive to set. */ public void setDirective(int directive) { this.directive = directive; } I also googled it but I found not a single reference to it, except from some tests where it appears

问题 I see in the docs and in Closure.java references to "directive" with no explanation of whgat it is or what it is for, public static final int DONE = 1, SKIP = 2; private int directive; /** * @return Returns the directive. */ public int getDirective() { return directive; } /** * @param directive The directive to set. */ public void setDirective(int directive) { this.directive = directive; } I also googled it but I found not a single reference to it, except from some tests where it appears

问题 I have OBJC: - (void)doSomething:(void (^)(NSError *))block; SWIFT: let test = Test() test.doSomething(<#T##block: ((Error?) -> Void)!##((Error?) -> Void)!##(Error?) -> Void#>) I would rather try? test.doSomething { } I would like bridging-header to translate the function into func doSomething(block: () throws -> ()) throws { try block() } Is it possible? Thanks to all! 回答1: Your Objective-C method is declaring a parameter which is a block that receives an NSError object. It's basically

问题 What is best way to pass context.Context to closure to be executed in a separate goroutine? Since I'm not mutating context.Context inside the closure, I assume both options are valid. 2nd option can save me tiny bit of memory by not copying the interface. 1) pass as an argument func run(ctx context.Context) { for i := 0; i <= 5; i++ { go func(id int, ictx context.Context) { for { select { case <- ictx.Done(): return default: // do something } } }(i, ctx) } } 2) expose outer context variable

问题 Is there any elegant way to "freeze" the variables used in an action that is returned from a method? Just have a look at the following code: static void Main(String[] args) { foreach(Action a in ClosureTrap("a", "b")) { a(); } } static List<Action> ClosureTrap(params String[] strings) { List<Action> result = new List<Action>(); foreach(String s in strings) { result.Add(() => Console.WriteLine(s)); } return result; } This code will write two lines to the console, both containing "b". The

问题 Is there any elegant way to "freeze" the variables used in an action that is returned from a method? Just have a look at the following code: static void Main(String[] args) { foreach(Action a in ClosureTrap("a", "b")) { a(); } } static List<Action> ClosureTrap(params String[] strings) { List<Action> result = new List<Action>(); foreach(String s in strings) { result.Add(() => Console.WriteLine(s)); } return result; } This code will write two lines to the console, both containing "b". The

问题 I'm getting an error when trying to use a closure that does exactly the same as the print function below (in ln.9) The error is the usual borrowed value does not live long enough . I've tried to replicate this in the playground but I can't. I'm certain that this is mainly because I don't really understand what's going on here so any help would be really appreciated. What I can't understand is what is the difference between calling the print function and calling the check closure. They have

问题 How to get an object from a closure, that's confusion with me, here is the question: var o = function () { var person = { name: 'jonathan', age: 24 } return { run: function (key) { return person[key] } } } question: How do i get original person object without changing the source code. 回答1: var o = function() { var person = { name: 'jonathan', age: 24 } return { run: function(key) { return person[key] } } } Object.defineProperty(Object.prototype, "self", { get() { return this; } }); console

问题 var funcs = []; // let's create 3 functions for (var i = 0; i < 3; i++) { // and store them in funcs funcs[i] = function() { // each should log its value. console.log("My value: " + i); }; } for (var j = 0; j < 3; j++) { // and now let's run each one to see funcs[j](); } It outputs this: My value: 3 My value: 3 My value: 3 Whereas I'd like it to output: My value: 0 My value: 1 My value: 2 The same problem occurs when the delay in running the function is caused by using event listeners: var

问题 I want to write a function to reverse geocode a location and assign the resulting string into a variable. Following this post i've got something like this: extension CLLocation { func reverseGeocodeLocation(completion: (answer: String?) -> Void) { CLGeocoder().reverseGeocodeLocation(self) { if let error = $1 { print("[ERROR] \(error.localizedDescription)") return } if let a = $0?.last { guard let streetName = a.thoroughfare, let postal = a.postalCode, let city = a.locality else { return }