class

Operator overloading in Python: handling different types and order of parameters [duplicate]

由 北城余情 提交于 2020-04-08 00:50:08
问题 This question already has an answer here : Python commutative operator override (1 answer) Closed 2 years ago . I have a simple class that helps with mathematical operations on vectors (i.e. lists of numbers). My Vector can be multiplied by other instances of Vector or a scalar ( float or int ). In other, more strongly typed, languages I would create a method to multiply two vector s and a separate method to multiply a vector by and int / float . I'm still pretty new to Python and am not sure

How to pass props from one class to another in React.js

由 試著忘記壹切 提交于 2020-04-07 18:55:11
问题 I'm very new to React. I'm practicing by creating a very simple nine grid box, where a user can select what color they want to use at the moment by using a dropdown menu. The only thing is, I can't quite figure out how to pass the variable from the class that contains it (ColorPicker) to the the class that contains the grids (Box). Can anyone give me some pointers on how to do this? I'm still getting used to passing props to other classes. Here's a link to the CodePen: http://codepen.io

黑马程序员--java基础加强之反射(Reflection)

由 ℡╲_俬逩灬. 提交于 2020-04-07 06:56:36
------- android培训 、 java培训 、期待与您交流！ ---------- 反射 一、反射的基石-->Class类 1、java类的作用：是用来描述一类事物的共性，有什么属性，没有什么属性，至于属性的值是什么，则由这个类的实例对象来确定的，而不同的 实例对象就有不同的属性值。 2、Class类的产生：java程序中的各个java类也属于同一类事物，所以也可以用一个类来描述这些事物，这个类就是Class。 例如：众多的人需要建一个Person类，同理众多的类需要建一个Class类。 二、Class类介绍 1、创建Class类的的引用：Class class = 字节码(Person.class); 字节码：每个类编译后会产生一个.class文件，该文件就是字节码。 1)类名.class，如：System.class； 2)对象.getClass(),如：new Date().getClass(); 3)Class.forName("类名")，如：Class.forName("java.lang.String")； 该方法在反射中常用，用时将类名作为变量传入。 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 public class ReflectionClass { public static

虚方法，抽象类，重写

由 徘徊边缘 提交于 2020-04-07 05:28:05
abstract可以修饰classes、methods、properties、indexers和events。如果某个class的声明被abstract修饰，那么就表示这个class用来做为父类的，是要被其他class继承的。如果某个class的成员被修饰为abstract，或者这个class被abstract修饰，那么继承这个class的class必须实现这些成员。 被abstract修饰的class有以下特点： 1、abstract class不能被实例化。 2、abstract class可以包含0个或多个abstract成员。 3、abstract的成员方法，只有成员声明 + “;”，没有方法体。 4、abstract的方法将在非abstract的子类中实现。 5、被abstract修饰的方法不可以再被virtual和static修饰。 6、properties已经被static修饰，它不可以再被abstract修饰。 7、abstract成员可以在子类中通过override修饰符被重写。 如果abstract class继承了接口，就需要把接口中所有的方法实现或者映射成abstract方法。 virtual virtual 关键字用于修改方法或属性的声明，在这种情况下，方法或属性被称作虚拟成员。虚拟成员的实现可由派生类中的重写成员更改。 调用虚方法时

PHP: override parent class properties from child class

由 妖精的绣舞 提交于 2020-04-07 04:04:06
问题 Maybe you know some "right-way" to override class property from child class method <?php class A { public $option; public function __construct() { $this->option = array(1,2,3); } public function bb() { $obj = new B; $obj->aa(); print_r($this->option);die; } } class B extends A { public function __construct() { parent::__construct(); } public function aa() { $this->option[] = 4; //print_r($this->option);die; } } $obj3 = new A; $obj3->bb(); ?> returns Array ( [0] => 1 [1] => 2 [2] => 3 )

PHP: override parent class properties from child class

由 寵の児 提交于 2020-04-07 03:57:53
问题 Maybe you know some "right-way" to override class property from child class method <?php class A { public $option; public function __construct() { $this->option = array(1,2,3); } public function bb() { $obj = new B; $obj->aa(); print_r($this->option);die; } } class B extends A { public function __construct() { parent::__construct(); } public function aa() { $this->option[] = 4; //print_r($this->option);die; } } $obj3 = new A; $obj3->bb(); ?> returns Array ( [0] => 1 [1] => 2 [2] => 3 )

Javascript ES6 shared class variable

由 主宰稳场 提交于 2020-04-07 03:48:06
问题 I have a class that looks like this: class Foo { constructor(arg1, arg2) { // ... this._some_obj = new SomeObj({ param1: arg1, param2: arg2 }); } // ... } module.exports = Foo; Now I want to do the same thing but with _some_obj shared between all instances of the class. After searching around I'm unclear as to the correct way to do this in ES6. 回答1: As known from ES5, you can just put it on the class's prototype object: export class Foo { constructor(arg1, arg2) { … } … } Foo.prototype._some

C# using system.io not woking in my class but works in main

由 我是研究僧i 提交于 2020-04-06 22:25:07
问题 I am working on an issue I do not remember ever having before. I am using VS2012 C# When i add using System.IO ; to my main program everything works fine, however when I add it to my class file it will not let me use all of the methods. using System; using System.Collections.Generic; using System.IO; using System.Data.SQLite; using System.Linq; using System.Text; using System.Threading.Tasks; namespace FoxySearch { class FoxySearch { File. <<<<----- here i want to add File.Exists("Blablalba")

C# what difference enum in namespace than enum inside a class

由 吃可爱长大的小学妹 提交于 2020-04-06 05:51:37
问题 i have a question about enums that the codes are below: namespace space { public enum MyEnums { Enum1,Enum2,... } } namespace space { public class MyClass { public enum MyEnums { Enum1,Enum2,... } } } whats difference and how to use them? 回答1: Well syntactically the only difference is that you'd preface the enum type with the containing class: MyClass.MyEnums.Enum1 versus just MyEnums.Enum1 (in both cases the namespace is assumed to be covered with a using directive) However, containing it

CSS美化简单网站首页

由 喜夏-厌秋 提交于 2020-04-05 17:22:41
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>网站首页美化版</title> <style> .top{ float: left; width: 33%; height: 65px; } .amenu{ color: white; text-decoration: none; line-height: 50px; } .price{ color: red; } .pot{ float: left; width: 16.66%; height: 50%; text-align: center; } </style> </head> <body> <div> <div class="top"><img src="img/6.png"/></div> <div class="top"><img src="img/5.jpg"/></div> <div class="top" style="line-height: 50px; text-align: center;"> <a href="#">登录</a> <a href="#">注册</a> <a href="#">购物车</a> </div> </div> <div style="clear: both;"></div> <div style="height:
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