closures

问题 I would love to use closures in Java. I have read that they may or may not make it into Java 7. But an open-source project called functional-java has implemented functional features including closures. How safe would it be to use such a library in an enterprise production app? Is there a better way to add closures to Java currently? 回答1: Closures will definitely not make it into Java 7, due to a lack of consensus around a single implementation. See here. The Functional Java library is

问题 I was asked what's the relationship between partial function application and closures. I would say there isn't any, unless I'm missing the point. Let's say I'm writing in python and I have a very simple function MySum defined as follows: MySum = lambda x, y : x + y; Now I'm fixing one parameter to obtain a function with smaller arity which returns the same value that MySum would return if I called it with the same parameters (partial application): MyPartialSum = lambda x : MySum(x, 0); I

问题 For an explanation of closures in general, see How do JavaScript closures work? How exactly are Go closures laid out in memory? Take, for example, the following function: type M int func (m *M) Adder(amount int) func() { return func() { *m = *m + amount } } When our code calls a := m.Adder() , how much memory is allocated on the heap and what does it look like? How much memory does the returned func() value take up (wherever in memory it ends up being)? 回答1: The Go Programming Language

问题 Hi I have a String value that is populated runtime and I want to use it to construct another String. static value= '' static construct = "${-> value - '/'}" So when I value = "/www.stackoverflow.com" , construct is equal to "www.stackoverflow.com" but when I do static value= '' static construct = {-> value - '/'} construct is equals to some closure name . I am wondering what is the purpose of this? Why using closure,GString everything is ok? And why when use only closure nothing happens?

问题 I'm trying to figure out how I can have a javascript function privately track the number of times it has been called. The objective is to be able to query this value in the console during debugging by doing func.run My first attempt: function asdf() { if (!asdf.run) { asdf.run = 0; } else { asdf.run++; console.error('run: ' + asdf.run); } console.error('asdf.run def: '); console.error(asdf.run); } asdf(); This is a good lesson of why one should ALWAYS aim to use === in nearly all javascript

问题 I'm trying to build a counter in python with the property of closure. The code in the following works: def generate_counter(): CNT = [0] def add_one(): CNT[0] = CNT[0] + 1 return CNT[0] return add_one However when I change the list CNT to a var, it did not work: def generate_counter1(): x = 0 def add_one(): x = x + 1 return x return add_one when I print the closure property of an instance, I found the __closure__ of the second case is none: >>> ct1 = generate_counter() >>> ct2 = generate

问题 Looking at the docs for the .each() function in jquery shows the following method signature: .each( function(index, Element) ) http://api.jquery.com/each/ I can understand needing to pass in an index so that it is available for use within the callback but why would you explicitly include the Element parameter if you can just reference the current element by the this keyword? Is it there just so that you can specify an instance name of your choice? I mean, if you still have to wrap a named

问题 The below example was taken from the book, "Javascript: The good parts". The author says that the helper function returns a function that binds to the current value of var i . Can anyone explain what makes it to bind the VALUE instead of REFERENCE of var i , because helper function is a closure to add_the_handler function and should only see the reference of var i : var add_the_handlers = function (nodes) { var helper = function (i) { return function (e) { alert(i); }; }; var i; for (i = 0; i

问题 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() } 回答1: This works for me with Groovy 1.7.3: someClosure = { assert "apple" == a } void

问题 I made a utility debug class in a C# game I'm working on to be able to monitor and watch values of properties. Goes like this: public static class Monitor { private static List<object> monitoredObjects; public static void Initialize() { monitoredObjects = new List<object>(); } public static void Watch(object o) { monitoredObjects.Add(o); } public static void Unwatch(object o) { monitoredObjects.Remove(o); } public static void Draw(RenderWindow app) { //Not actual code, I actually draw this in