scope

问题 I have the following Obj C function that works properly: NSString* myfunc( int x ) { NSString *myString = @"MYDATA"; return myString; } However if I add code to update a UIImage the compile fails with image1 being unknown. image1 is valid: it's set up in the .h, synthesized and that exact line of code works in a method below this function. Only when I move the line of code up to this function does it fail. NSString* myfunc( int x ) { NSString *myString = @"MYDATA"; image1.image = [UIImage

问题 I have the following VBA code. Option Explicit Sub problem1() Dim speedmph As Double, speedkph As Double, speedfts As Double speedmph = Val(InputBox("Enter a speed (mph)")) Call convert(speedmph, speedkph, speedfts) MsgBox "The speed is " & speedkph & " km/hr and " & speedfts & "ft/s." End Sub Sub convert(speedmph, speedkph, speedfts) speedkph = speedmph * 1.609 speedfts = speedmph * 1.467 End Sub I've noticed that when I called the convert procedure as it is shown above, it worked. But if I

问题 I get this out put =============================== RESTART: Shell =============================== >>> Warning (from warnings module): File "E:/Python/Roy Progs/test.py", line 2 global x SyntaxWarning: name 'x' is assigned to before global declaration >>> ==================== RESTART: E:/Python/Roy Progs/test.py ==================== 10 >>> when I run this code. x=5 global x x=10 print x Yes I know that defining a variable after assigning it a value is absurd, however python seems to understand

问题 Normally I'd assign an alternative "self" reference when referring to "this" within setInterval. Is it possible to accomplish something similar within the context of a prototype method? The following code errors. function Foo() {} Foo.prototype = { bar: function () { this.baz(); }, baz: function () { this.draw(); requestAnimFrame(this.baz); } }; 回答1: Unlike in a language like Python, a Javascript method forgets it is a method after you extract it and pass it somewhere else. You can either

问题 Let's say I got a global variable called myData. It was declared as myData = 1; at the beginning of a script. Goal: I want to create a single module that will not have access this myData in any way. myData must remain global in other modules. Note: Yes, I already do know that I could require myData in every page where I need it but that's not what I'm looking for. Attempts: To do that, at the very beginning of the module, I wrote: var myData; . The module could no longer access myData

问题 I have a select element that should be filled with some options that I need to retrieve from an API call, then set the first one as selected. But Angular creates an empty option at first position and I don't know how to delete it. Here's my code: HTML <select class="form-control" ng-model="selectedPositionFamily"> <option ng-repeat="pf in positionFamilies" ng-value="pf.uuid">{{pf.name}}</option> </select> Controller function Controller($scope, PositionFamilyService) { $scope.positionFamilies

问题 I create all the variables within the same function. But at the end of the function I can't reach the constant even though it was created in the same function. When I write "self.resultLabel.text = weather" at the end, Xcode shows me an error use of unresolved identifier 'weather' I know how to fix it. I need to initiate 'weather' just after the task method starts and set it to "" and then I should change its value in the function but even if I don't do it and I create it in the if closures,

问题 This question already has answers here : Javascript function scoping and hoisting (16 answers) Closed 5 years ago . why does the following code segment generate the following output? code segment: var a = 10; function(){ console.log(a); var a = 5; } output: undefined 回答1: Because variable is hoisted at top and in your function you have declared the variable var a = 5 which is same as following: var a = 10; function(){ var a; // a = undefined console.log(a);//a is not defined so outputs

问题 In order to make function calls to our back-end php code we've implemented something called an ActionProxy like this: function ActionProxy(action, input, callback){ $.post("ActionProxy.php?method="+action, { data: input}, function(data, textStatus, XMLHttpRequest){ //return data.ResponseWhatever } }); The problem we're having is that using data outside the ActionProxy is impossible due to variable scope limitations (we assume), setting var res = data.ResponseWhatever or return data

问题 function grabSourceFile { cd /tmp/lmpsource wget $1 > $LOG baseName=$(basename $1) tar -xvf $baseName > $LOG cd $baseName } When I call this function The captured output is not going to the log file. The output redirection works fine until I call the function. The $LOG variable is set at the top of the file. I tried echoing statements and they would not print. I am guessing the function captures the output itself? If so how do push the output to the file instead of the console. (The wget