scope

问题 I have code with the following form: <?php function doSomething{ //Do stuff with MySQL $con->tralalala(); } $con = connectToDatabase;//This would actually be a line or two. doSomething(); ?> This (type of) code doesn't work, because doSomething() doesn't have a connection to the database. Can anyone explain why not? I create the $con connection before I call doSomething(). So why does the function act as if there's no connection? Is there any way to fix this, short of passing the connection

问题 I'm new to Swift and I'm trying to get the result from this function. I don't know how to access variables that are inside the closure that is passed to the sendAsynchronousRequest function from outside the closure. I have read the chapter on closures in the Apple Swift guide and I didn't find an answer and I didn't find one on StackOverflow that helped. I can't assign the value of the 'json' variable to the 'dict' variable and have that stick outside of the closure. var dict: NSDictionary!

问题 Normally it would be destructed upon the scope ending.. I could see issues occurring if exceptions were thrown though. 回答1: Yes. C++ Standard n3337 15 Exception handling § 15.2 Constructors and destructors 1) As control passes from a throw-expression to a handler, destructors are invoked for all automatic objects constructed since the try block was entered . The automatic objects are destroyed in the reverse order of the completion of their construction. 2) An object of any storage duration

问题 I have declared a function in file so that it becomes global: function speakService() { var speakService = {}; var speak = function(word) { console.log(word); }; speakService.speak = speak; return speakService; } Using AngularJS, I want to add this service as dependency: angular .module('login', ['ngRoute']) .factory('speakService', [function() { var speakService = speakService(); return speakService; }]); But as soon as the interpreter hits the line: var speakService = speakService(); the

问题 I have declared a function in file so that it becomes global: function speakService() { var speakService = {}; var speak = function(word) { console.log(word); }; speakService.speak = speak; return speakService; } Using AngularJS, I want to add this service as dependency: angular .module('login', ['ngRoute']) .factory('speakService', [function() { var speakService = speakService(); return speakService; }]); But as soon as the interpreter hits the line: var speakService = speakService(); the

问题 I'm learning Perl and trying to understand variable scope. I understand that my $name = 'Bob'; will declare a local variable inside a sub , but why would you use the my keyword at the global scope? Is it just a good habit so you can safely move the code into a sub? I see lots of example scripts that do this, and I wonder why. Even with use strict , it doesn't complain when I remove the my . I've tried comparing behaviour with and without it, and I can't see any difference. Here's one example

问题 I'm coming from Knockout and I'm trying to understand how Angular updates the scope. I'm a bit confused as to why a function defined on the scope (e.g. $scope.doStuff = function() ) gets executed on every single scope refresh. Plnkr link: http://plnkr.co/edit/YnvOELGkRbHOovAWPIpF?p=preview For example: HTML <div ng-controller="one"> <input type="text" ng-model="a"> {{b()}} </div> JS angular.module('test', []) .controller('one', ['$scope', function ($scope) { $scope.a = 'one'; $scope.b =

问题 Studying JSR-299, I read the section 5.1 of the Weld reference which explains how scopes works in CDI. Apparently, context is a concept closely related to scope. I have understood a bit about what each one is but it is not very clearly separated in my mind and I feel tempted to even use the words interchangeably. What is the difference between scope and context? What is the relationship between the two concepts? I expect an answer in the CDI domain but it is a doubt I have about Java in

问题 In javascript, What is the difference between function declaration and function expression in terms of scope? function declaration means we are polluting the global space. Is it the same case with function expression? Function declaration function sum(){ // logic goes here } Function expression var sum = function(){} 回答1: As far as polluting the enclosing scope goes, both are equivalent. Note that it is not necessarily the global scope - it is the scope in which the function is declared

问题 I accidentally happened to find this in one of the source codes I was looking at. So, I'm giving a similar smaller example here. In the file test.h : #include<iostream> class test{ int i; public: test(){} //More functions here }; In the file test.cpp : #include "test.h" int main() { test test1; test::test test2; test::test::test test3; return 0; } First of all, is there a reason to declare test2 that way? Secondly, this code compiles just fine in g++ version 4.4.3 and lower versions. Is there