closures

Anonymous functions in WordPress hooks

由 删除回忆录丶 提交于 2019-12-04 10:16:54
问题 WordPress hooks can be used in two ways: using callback function name and appropriate function add_action( 'action_name', 'callback_function_name' ); function callback_function_name() { // do something } using anonymous function (closure) add_action( 'action_name', function() { // do something } ); Is there any difference for WordPress what way to use? What is prefered way and why? 回答1: The disadvantage of the anonymous function is that you're not able to remove the action with remove_action.

How does local() differ from other approaches to closure in R?

由 ♀尐吖头ヾ 提交于 2019-12-04 10:10:12
问题 Yesterday I learned from Bill Venables how local() can help create static functions and variables, e.g., example <- local({ hidden.x <- "You can't see me!" hidden.fn <- function(){ cat("\"hidden.fn()\"") } function(){ cat("You can see and call example()\n") cat("but you can't see hidden.x\n") cat("and you can't call ") hidden.fn() cat("\n") } }) which behaves as follows from the command prompt: > ls() [1] "example" > example() You can see and call example() but you can't see hidden.x and you

Swift weakSelf in closure syntax

由 自闭症网瘾萝莉.ら 提交于 2019-12-04 09:41:08
问题 I have this code to get JSON: Alamofire.request(.GET, worlds).responseJSON { (request, response, JSON, error) in println(JSON) //weakSelf.serverList = JSON } How to declare weakSelf here? I know it should be unowned in my case, but I can't find correct syntax for this. When I try use [unowned self].serverList instead of the commented line, the compiler shows me error "use of unresolved identifier 'unowned'". I also tried to declare constant before block like this: unowned let uSelf = self It

Problem with delegates in C#

由 霸气de小男生 提交于 2019-12-04 09:34:46
问题 In the following program, DummyMethod always print 5. But if we use the commented code instead, we get different values (i.e. 1, 2, 3, 4). Can anybody please explain why this is happenning? delegate int Methodx(object obj); static int DummyMethod(int i) { Console.WriteLine("In DummyMethod method i = " + i); return i + 10; } static void Main(string[] args) { List<Methodx> methods = new List<Methodx>(); for (int i = 0; i < 5; ++i) { methods.Add(delegate(object obj) { return DummyMethod(i); });

Why can an anonymous class access non-final class member of the enclosing class

由 倖福魔咒の 提交于 2019-12-04 09:12:47
问题 We know that only final local variables can be accessed in an anonymous class, and there is a good reason here: Why are only final variables accessible in anonymous class?. However, I found that an anonymous class can still access a non-final variable if the variable is an member field of the enclosing class: How can I access enclosing class instance variables from inside the anonymous class? I am confused. We ensure that only a final local variable can be accessed in anonymous class because

binding and closures groovy

由 筅森魡賤 提交于 2019-12-04 08:58:45
I don't know how to use binding with closures in Groovy. I wrote a test code and while running it, it said, missing method setBinding on the closure passed as parameter. void testMeasurement() { prepareData(someClosure) } def someClosure = { assertEquals("apple", a) } void prepareData(testCase) { def binding = new Binding() binding.setVariable("a", "apple") testCase.setBinding(binding) testCase.call() } This works for me with Groovy 1.7.3: someClosure = { assert "apple" == a } void testMeasurement() { prepareData(someClosure) } void prepareData(testCase) { def binding = new Binding() binding

Variable captured by closure before being initialized

由 末鹿安然 提交于 2019-12-04 08:49:43
问题 I'm trying to store the number of results from a query into an integer so that I can use it to determine the number of rows in a table. However, I'm getting the following error: Variable 'numberOfGames' captured by a closure before being initialized' on the line query.findObjectsInBackgroundWithBlock{ . I also get another error Variable 'numberOfGames' used before being initialized on the line return numberOfGames . Here's the function that contains the two errors: func tableView(tableView:

Closures in Scala vs Closures in Java

由 ⅰ亾dé卋堺 提交于 2019-12-04 08:15:23
问题 Some time ago Oracle decided that adding Closures to Java 8 would be an good idea. I wonder how design problems are solved there in comparison to Scala, which had closures since day one. Citing the Open Issues from javac.info: Can Method Handles be used for Function Types? It isn't obvious how to make that work. One problem is that Method Handles reify type parameters, but in a way that interferes with function subtyping. Can we get rid of the explicit declaration of "throws" type parameters?

Store state of a JavaScript Object

由 做~自己de王妃 提交于 2019-12-04 07:56:08
Im trying to store the stats of 'this' in my javscript object so that later on in my application I can return 'this' to a previous state. I thought I could accomplish using a closure but so far I haven't successful. My idea was to do something like this function SavedFeature() { var self = this; this.savedItem; this.storeState = function() { this.savedItem = storeClosure(); } function storeClosure() { var closure = self; return function() { return closure; }; }; //other things the user can change... } so later on in my application if I needed to return to the point when I called storeState I

How do `map` and `reduce` methods work in Spark RDDs?

由 試著忘記壹切 提交于 2019-12-04 07:49:55
问题 Following code is from the quick start guide of Apache Spark. Can somebody explain me what is the "line" variable and where it comes from? textFile.map(line => line.split(" ").size).reduce((a, b) => if (a > b) a else b) Also, how does a value get passed into a,b? Link to the QSG http://spark.apache.org/docs/latest/quick-start.html 回答1: First, according to your link, the textfile is created as val textFile = sc.textFile("README.md") such that textfile is a RDD[String] meaning it is a resilient
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