virtual

类的多态

此生再无相见时 提交于 2019-12-02 06:47:59
运算符重载 不能重载的运算符 类属关系运算符“.” 成员指针运算符“.*” 作用域分辨符“::” 三目运算符“?:” 重载运算符 重载运算符函数必须要有重载的类在参数里面 成员重载运算符 调用时,必须是类对象进行调用,且会将自己自动传入做 this 双目运算符操作时,该类对象必须出现在左边,以进行调用 单目运算符操作时,int有是后置++/--,无是前置++/-- 非静态成员 #include using namespace std; class Clock { public: Clock(int hour = 0, int minute = 0, int second = 0); void showTime() const; Clock &operator++(); //前置单目运算符 Clock operator++(int); //int用于区分前置还是后置运算符 后置单目运算符 private: int hour, minute, second; }; void Clock::showTime() const{ cout 非成员运算符 用来解决调用对象不是类对象的情况(但参数还是要有类对象存在) 非成员 #include using namespace std; //非成员函数解决"复数+类"的情况,成员的运算符重载只能做到第一个参数是类类型的 class Complex

理解 Virtual DOM(摘)及评价

假如想象 提交于 2019-12-02 06:08:26
框架并没有提高web的性能,只是让开发者更加专注的完成业务逻辑,而不用过渡的考虑性能上的优化。如果以性能来比的话,框架是绝对比不过优化后的原生代码的。 二、什么是 Virtual DOM Virtual DOM的概念有很多解释,从我的理解来看,主要是三个方面,分别是:一个对象,两个前提,三个步骤。 一个对象指的是Virtual DOM是一个基本的JavaScript对象,也是整个Virtual DOM树的基本。 两个前提分别是JavaScript很快和直接操作DOM很慢,这是Virtual DOM得以实现的两个基本前提。得益于V8引擎的出现,让JavaScript可以高效地运行,在性能上有了极大的提高。直接操作DOM的低效和JavaScript的高效相对比,为Virtual DOM的产生提供了大前提。 三个步骤指的是Virtual DOM的三个重要步骤,分别是:生成Virtual DOM树、对比两棵树的差异、更新视图。这三个步骤的具体实现也是本文将简述的一大重点。 五、进一步思考 Virtual DOM的原理和实现的说明已经结束了,但是对于Virtual DOM的思考远没有结束,Virtual DOM 对前端开发的影响难道就只是一堆算法吗? 1 、性能对比 首先,先来看一下性能,在诸多的Virtual DOM实现中,都会强调算法的高效,那么在实际的使用中,Virtual

ovs ovn 学习资料

三世轮回 提交于 2019-12-02 05:32:51
0、A Primer on OVN http://blog.spinhirne.com/2016/09/a-primer-on-ovn.html 1、Open Virtual Networking With Docker http://docs.openvswitch.org/en/latest/howto/docker/ 2、Multi-Host Docker network https://wiredcraft.com/blog/multi-host-docker-network/ 3、ovn-namespace https://github.com/shettyg/ovn-namespace 4、OVN简介PPT http://openvswitch.org/support/slides/OVN_Barcelona.pdf 5、What is Open Virtual Network (OVN)? How It Works (包含了各种关于网络虚拟化的介绍的连接) https://www.sdxcentral.com/sdn/network-virtualization/definitions/what-is-open-virtual-network-ovn-how-it-works/ 6、Open vSwitch 相关论文 http://openvswitch.org

Virtual function keyword

◇◆丶佛笑我妖孽 提交于 2019-12-02 04:07:58
Is there any difference between declaring inherited virtual function in a child class with the "virtual" keyword or not , considering I want to call fun appropriate to my objects' type. Look at the comments. #include <cstdio> struct A{ int a; A():a(5){} virtual int fun(){return a+1;} }; struct B: public A{ virtual int fun(){return a+5;} //I put virtual here // int fun(){return a+5;} // Any difference if I put virtual before or not? }; int main(){ B obj; printf("%d\n", static_cast<A>(obj).fun()); // A::fun() called. Why? printf("%d\n", static_cast<A&>(obj).fun()); // B::fun() called. As

What's the difference between virtual function instantiations in C++?

别等时光非礼了梦想. 提交于 2019-12-02 03:14:08
What's the difference between the following two declarations? virtual void calculateBase() = 0; virtual void calculateBase(); I read the first one (=0) is a "pure abstract function" but what does that make the second one? First one is called a pure virtual function. Normally pure virtual functions will not have any implementation and you can not create a instance of a class containing a pure virtual function. Second one is a virtual function (i.e. a 'normal' virtual function). A class provides the implementation for this function, but its derived class can override this implementation by

Can I tell if a C++ virtual function is implemented

谁说胖子不能爱 提交于 2019-12-02 03:07:42
I want to be able to tell at run-time if an instance of a class implements a virtual function. For example: struct Base { virtual void func(int x) { <default behavior here> } virtual void func2(int x) { <default behavior here> } }; struct Deriv : Base { virtual void func(int x) override { <new behavior here> } }; int main() { Base *d = new Deriv; if(implements<Base::func(int)>(d)) // This should evaluate true {} if(implements<Base::func2(int)>(d)) // This should evaluate false {} } I have seen this but it's dated and there might be a something that c++11/14 has to say now: Ways to detect

C# -- Abstract和Virtual学习

雨燕双飞 提交于 2019-12-02 02:32:15
一、Virtual方法(虚方法) 1:virtual 关键字用于在基类(父类)中修饰方法。virtual的使用会有两种情况: (1):在基类中定义了virtual方法,但在派生类中没有重写该虚方法。那么在对派生类实例的调用中,该虚方法使用的是基类定义的方法,比如在一个Book类中有一个虚方法InitDate(),然后一个Fiction类继承了Book类,但是在该类中并没有实现InitDate()这个方法,那么实例Fiction类使用方法的还是Book类中的虚方法 (2):在基类中定义了virtual方法,然后在派生类中使用override重写该方法。那么在对派生类实例的调用中,该虚方法使用的是派生重写的方法。 二、Abstract方法(抽象方法) 1: abstract关键字只能用在抽象类中修饰方法,并且没有具体的实现。抽象方法的实现必须在派生类中使用override关键字来实现。 2:接口和抽象类最本质的区别:抽象类是一个不完全的类,是对对象的抽象,而接口是一种行为规范。 3: C# 是面向对象的程序设计语言,每一个函数都属于一个类。 4:Static:当一个方法被声明为Static时,这个方法是一个静态方法,编译器会在编译时保留这个方法的实现。也就是说,这个方法属于类,但是不属于任何成员,不管这个类的实例是否存在,它们都会存在。就像入口函数Static void Main

position of virtual keyword in function declaration

白昼怎懂夜的黑 提交于 2019-12-01 23:43:00
问题 Does it make any difference whether I place the virtual keyword in a function declaration before or after the return value type? virtual void DoSomething() = 0; void virtual DoSomething() = 0; Found the void virtual syntax while refactoring some legacy code, and was wondering that it is compiling at all... 回答1: Both the statements are equivalent. But the 1st one is more conventional. Because, generally mandatory fields are kept closest to any syntax (i.e. the function prototype in your

position of virtual keyword in function declaration

◇◆丶佛笑我妖孽 提交于 2019-12-01 22:40:34
Does it make any difference whether I place the virtual keyword in a function declaration before or after the return value type? virtual void DoSomething() = 0; void virtual DoSomething() = 0; Found the void virtual syntax while refactoring some legacy code, and was wondering that it is compiling at all... Both the statements are equivalent. But the 1st one is more conventional. Because, generally mandatory fields are kept closest to any syntax (i.e. the function prototype in your example). virtual is an optional keyword (it's needed for pure virtual though). However return type (here void )

Window10安装Hyper-V的条件

妖精的绣舞 提交于 2019-12-01 22:06:27
Windows 10 Hyper-V System Requirements In this article Operating System Requirements Hardware Requirements Verify Hardware Compatibility Hyper-V is available in 64-bit version of Windows 10 Pro, Enterprise, and Education. Hyper-V requires Second Level Address Translation (SLAT) -- present in the current generation of 64-bit processors by Intel and AMD. You can run 3 or 4 basic virtual machines on a host that has 4GB of RAM, though you'll need more resources for more virtual machines. On the other end of the spectrum, you can also create large virtual machines with 32 processors and 512GB RAM,