scope

问题 I have the following code: if entryJson, err := json.MarshalIndent(entry, "", " "); err != nil{ log.Println(err) } else { log.Println(entryJson) } if err := ioutil.WriteFile("text.json", entryJson, 0644); err != nil { log.Println(err) } I want to limit the scope of err as much as possible. The problem I'm facing with this is, that the variable entryJson is out of scope when I want to write it to the file. What is the idiomatic way to deal with this. Should I just reuse the variable err and

问题 I have a working program which must be split into multiple parts, for edition purposes. In this program is needed to keep user login info in char arrays to be able to connect to SQL, and this connection info is used many times in parts of the program that will end up in separated .cpp files, which will compile in a single program. The problem is that if they are declared in just one file, they will be missing in the rest, and if they are declared in all of them, there will be duplicated

问题 I have a data frame Indices containing various names which correspond to data frames ( i.e. a name "Index 1" has a corresponding data frame Index 1 ). Now I want to run my custom function calcScores over all data frames and add several columns to that data frame. Since I'm not in the global environment I return that "new" data frame and want to assign it back to the original variable Index 1 , so Index 1 now has the new data frame with the added columns. Here's my code (no chance I can make

问题 i am new to php oop I have an two files Here is my code 1)info.php public $bd, $db1; class Connection { function connect() { $this->db = 'hello world'; $this->db1 = 'hi' } } 2) prd.php require_once 'info.php' class prdinfo { function productId() { echo Connection::connect()->$bd; echo Connection::connect()->$db1; } $prd = new prdinfo (); $prd->productId (); how i can echo my var in 2nd class i have tried in that way but i am not getting proper output Thanks 回答1: It should be something like

问题 I have the following working JS script in one of the sites I'm working on. I'm wondering why the variables 'countryEl' and 'zipEl' are accessible from within the function passed to Event.observe. Can anybody explain? Thanks in advance! <script type="text/javascript"> //<![CDATA[ document.observe("dom:loaded", function() { var form = $('shipping-zip-form'); var countryEl = form.down('#country'); var zipEl = form.down('#postcode'); Event.observe(countryEl, 'change', function () { var

问题 I'm sorry guys, the entire code is this. I given you the short form to be light, but I made many mistakes. So please, ignore the code written before and read this. At the bottom of the code you can find also the calls to the functions (They are in two other files.html) The problem is that the value that the three "window.alert" show (during the running of the second Function) is undefined, as there aren't the three declared var on top or they aren't global (var numero_giocatori; var numero

问题 Forgive me if this is an amateur question, I'm new to using APIs. I've been working with Firebase to store a "scores" list array which is used throughout my script. Within one of the Firebase functions, the value is updated, but the value isn't updated within the global scope. I'm not sure what I'm missing at this point. Here's a code snippet, the values of 0 and 1 are logged on console. window.global_counter = 0; window.score = 0; window.listScores = {"GMS":0, "Vacc":0, "CH":0, "GSF":0,

问题 I am struggling with what I know is a very basic question related to variable declaration. I've read everything I can find on variables but I don't know if my problem is related to 1) how I am declaring variables or 2) how I am setting the scope of the variables. To start, my understanding of variables in Meteor is that if I use var , then I am setting file-scope, which would make that variable available to every helper for that particular template. If I do not use var , it will be global and

问题 In a Scala web application, is lazy val scoped to the lifetime of the application server, or request scoped? I assume it is per request, but have not been able to find a definitive answer, thus the question. Thanks 回答1: lazy is a Scala feature, not related to web application programming. It means: evaluate only once on first access . If the variable is part of an object created per request, it will be lazily evaluated once per every request. If it is declared inside application-wide class (or

问题 I've written a class that looks like class Mesh { public: vector<Vertex> vs; } where Vertex is class Vertex { public: const double x, y, z; } I have a function which loads a Mesh from a file: shared_ptr<Mesh> load_mesh(string filename) { //.... vector<Vertex> vs; Vertex v(1, 2, 3); vs.push_back(v); return shared_ptr<Mesh>(Mesh(vs)); } My questions are concerning the scope of the Vertex and the vector . Will one or both go out of scope? Which (if any) of the alternatives are preferred? class