scope

问题 I sometimes use braces to isolate a block of code to avoid using by mistake a variable later. For example, when I put several SqlCommand s in the same method, I frequently copy-paste blocks of code, ending by mixing the names and executing twice some commands. Adding braces helps to avoid this situation, because using a wrong SqlCommand in a wrong place will result in an error. Here's an illustration: Collection<string> existingCategories = new Collection<string>(); // Here a beginning of a

问题 I'm new to JavaScript and therefore confused for the variable scope... I'm trying to load an image, and replace it with another URL when it doesn't exist. I have to do it in pure JavaScript. Here I got 2 versions extremely alike, but they perform differently. The only thing in common is: they don't work. The 3rd version requires a refresh and doesn't work under IE. d is the object with number attribute, which has no problem. Here is what they have in common .attr("xlink:href", function (d) {

问题 Is there a way to restrict extension methods in DSLs? Say I have a class structure like this: class Outer { fun middle(op: Middle.() -> Unit): Middle { val middle = Middle() middle.op() return middle } } class Middle { fun inner(op: Inner.() -> Unit): Inner { val inner = Inner() inner.op() return inner } } class Inner fun outer(op: Outer.() -> Unit): Outer { val outer = Outer() outer.op() return outer } I can then create a call like so: outer { middle { inner { middle { } // Here is the

问题 Just learning dependency injection, and I think I'm starting to understand it. Please tell me if I'm on the right track... E.g.: Are these two equivalent? /* injection method */ function <controller_name>($scope) {} <controller_name>.$inject = ['$scope']; /* other method */ var app = angular.module('myApp'); app.controller(<controller_name>, function($scope) {}); 回答1: First a little clarification: For dependency injection, it doesn't matter whether you declare a controller using a global

问题 Here is an example: function ChildF() { #Creating new function dynamically $DynFEx = @" function DynF() { "Hello DynF" } "@ Invoke-Expression $DynFEx #Calling in ChildF scope Works DynF } ChildF #Calling in parent scope doesn't. It doesn't exist here DynF I was wondering whether you could define DynF in such a way that it is "visible" outside of ChildF. 回答1: The other solutions are better answers to the specific question. That said, it's good to learn the most general way to create global

问题 This question already has answers here : How do I pass a variable by reference? (26 answers) Closed 5 years ago . In the python code below, variable number is passed to the function addone , and a local copy is operated on. The value of number stays the same. def addone(num): num = num + 1 print "function: added 1, now %d" % num number = 5 print "Before:", number addone(number) print "After:", number Output : Before: 5 function: added 1, now 6 After: 5 However, the behavior appears to be

问题 In the following code the callback function passed to wrap_map can't see the argument in the outer function, why? (see code comment for detail) public static function wrap_implode($ar, $wrap, $delim){ echo "wrap is $wrap"; //wrap is ok $res = array_map(function($val){ echo "wrap is $wrap"; //wrap is not set here! return $wrap. $val . $wrap; }, $ar); return implode($delim, $res); } 回答1: Because it is in another scope. If you want to use $wrap , try: function($val) use ($wrap){ //etc } Of

问题 namespace N { static int x = 5; } What could be the importance/use-cases of declaring having a static variable at namespace scope? 回答1: Annex D (Compatibility features) [C++03] D2: The use of the static keyword is deprecated when declaring objects in namespace scope. Use unnamed namespaces instead as mentioned in this post. static keyword imparts internal linkage to variables/objects in C as well as in C++ in namespace scope as others have mentioned in their posts. P.S: Thie feature has been

问题 This program fails to compile(using gcc-4.5). The error message says: error: ‘myType_t’ does not name a type 1 class abc{ 2 //typedef int myType_t; 3 4 public: 5 typedef int myType_t; 6 7 abc(); 8 myType_t fun1(); 9 }; 10 11 myType_t abc::fun1() 12 { 13 return 0; 14 } 15 16 int main() 17 { 18 abc abc1; 19 return 0; 20 } Now declaring typedef int myType_t; outside the class abc makes this compile. My confusion is, what is the problem if the return type of a member function is typedef'd inside

问题 I have an integer variable ( time ) in one view controller whose value I need in another view controller. Here's the code: MediaMeterViewController // TRP - On Touch Down event, start the timer -(IBAction) startTimer { time = 0; // TRP - Start a timer timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(updateTimer) userInfo:nil repeats:YES]; [timer retain]; // TRP - Retain timer so it is not accidentally deallocated } // TRP - Method to update the timer display -