class

问题 I've been working on end to end test in testcafe and in their documentation I found following solution for Page Model: class Page { constructor () { this.nameInput = Selector('#developer-name'); } } export default new Page(); I've been doing some research and I cannot get my head around why it is not resolved with an object literal: export const Page = { nameInput: Selector('#developer-name'); } What are consequences of using each of them? 回答1: The difference is significant but fundamentally

问题 I am fairly new to classes so I apologise if my problem is something very basic. I want to delete the Enemy when it goes off the screen. I searched this online and found a similar Stackoverflow page which I understood I need to do something like del Enemy however It doesn't seem to work. I have def __del__(self): print("object deleted") method in my Enemy class so it should output that it has been deleted. Here is my function in which I try to delete the object: def enemy_actions(enemies,

问题 I've imported a dataset into R where in a column which should be supposed to contain numeric values are present NULL . This make R set the column class to character or factor depending on if you are using or not the stringAsFactors argument. To give you and idea this is the structure of the dataset. > str(data) 'data.frame': 1016 obs. of 10 variables: $ Date : Date, format: "2014-01-01" "2014-01-01" "2014-01-01" "2014-01-01" ... $ Name : chr "Chi" "Chi" "Chi" "Chi" ... $ Impressions: chr

问题 How do I wrap a method around this Async section of codes so I can get the variable "doc" returned as a returned value so I can reuse this method? I can't declare a static method inside this class, and when I tried to use a void method, the variable "doc" can't be returned, and there's also errors in the code. class JsoupParseTask extends AsyncTask<String, Void, Document> { protected Document doInBackground(String... urls) { Document doc = null; try { doc = Jsoup.connect("https://jsoup.org//"

问题 Say I have class child() and class parent() . The parent has a constructor and a few other public methods, and the child is empty apart from a constructor. How do I go about calling a parent's methods inside of the child's constructor, as in: Class Parent { public function __construct() { // Do stuff (set up a db connection, for example) } public function run($someArgument) { // Manipulation return $modifiedArgument; } } Class Child extends Parent { public function __construct() { // Access

问题 In the post at Common Lisp class hierarchy, Rainer Joswig & Joshua Taylor carefully distinguish some of the differences between built-in Common Lisp types and classes , where classes form part of the CLOS extension to the baseline. The type/class (plus mop) distinctions are also reflected in Pfeil's comprehensive hierarchy diagram. Using the diagram, it seems possible to extract the two distinct hierarchies. In particular, I am currently most interested in the tops of the hierarchies; namely,

问题 I have the following function which controls the spawning of the enemies and what they do. At the end of it I create multiple enemies using the same constructor. However, when in the main loop I call the method of those objects I get a name error . My function: #cretating and manipulating enemies def enemy_actions(enemies): free_lanes = 0 free_lane_positions = [] new_enemies_lanes = [] #going through all lanes for i in lanes: lane_taken = i[1] if not lane_taken: #counting how many free lanes

问题 I'm trying to create a binary search tree but it doesn't seem to be working. I debugged it, and it says the root is null. I don't understand why it is null. I set it to null initially in the constructor, but then when I call the insert() method, it is no longer null, right? Can someone help me understand this. Thanks. #include "stdafx.h" #include <iostream> using namespace std; struct node { public: int value; node * left; node * right; }; class bTree { public: node * root; public: bTree();

问题 I know that i can extend abstract classes and interfaces through Java.extend , but how can i add custom methods, constructors and fields in class? I tried to like this, but it's not works: var MyClass = Java.extend(java.lang.Object, { myField1: java.lang.String, myField2: java.lang.Object, "<init>": function(arg1, arg2) { // Try to declare constructor }, myMethod: function(arg1, arg2, arg3) { // Try to declare method } }); 回答1: As A. Sundararajan correctly states, you can't add new features

问题 I'm working on a project using Python and Tkinter. I want to modularize it. One of the main problems is that the implementation of my Toplevel widget is too big. I heard that it's possible to put this widget in a new class. The problem is I don't know how. Here is how I define my main window: class App(tk.Tk): def __init__(self): tk.Tk.__init__(self) Config(self) So for my Toplevel widget I tried: class Config(tk.Toplevel): def __init__(self, main): tk.Toplevel.__init__(self) Is it the right