virtual

Overload,override和overwrite

由 做~自己de王妃 提交于 2019-12-26 08:50:58
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 在平时工作中，有时老被这些搞混乱，因此还是记录下来，以后方便检查。 C++： Overload(重载)：在C++程序中，可以将语义、功能相似的几个函数用同一个名字表示，但参数或返回值不同（包括类型、顺序不同），即函数重载。 （1）相同的范围（在同一个类中）； （2）函数名字相同； （3）参数不同； （4）virtual 关键字可有可无。 Override(覆盖)：是指派生类函数覆盖基类函数，特征是： （1）不同的范围（分别位于派生类与基类）； （2）函数名字相同； （3）参数相同； （4）基类函数必须有virtual 关键字。 Overwrite(重写)：是指派生类的函数屏蔽了与其同名的基类函数，规则如下： （1）如果派生类的函数与基类的函数同名，但是参数不同。此时，不论有无virtual 关键字，基类的函数将被隐藏（注意别与重载混淆）。 （2）如果派生类的函数与基类的函数同名，并且参数也相同，但是基类函数没有virtual 关键字。此时，基类的函数被隐藏（注意别与覆盖混淆）。 特别注意 如果基类有某个函数的多个重载（overload）版本，而你在子类中重写(overwrite)了其中的一个，或是子类添加新的函数版本，则所有基类的重载版本都被遮蔽。所以，正常情况下，在子类中应重写基类中的所有重载版本。 具体地讲

C# call abstract method from static method

由 ＊爱你＆永不变心＊ 提交于 2019-12-25 19:05:24
问题 i am writing library, that can be used for with different database engines. Abstract class has abstract DbParameter constructor and uses classes from System.Data.Common. Now i have sutch structure : public abstract class ASqlWorker{ abstract protected DbParameter DbParameterConstructor(String paramName, Object paramValue); } now, can i call abstract DbParameterConstructor from a static method of ASqlWorker? Logicaly, i could make abstractMethod static (it creates instance of an inheriter of

how to convert abstract class to normal class without overload pure virtual function?

由 ≡放荡痞女 提交于 2019-12-25 12:42:49
问题 look at following code: class A { public: virtual int getN() = 0; }; class B : public A { private: int n = 2; public: int getN() { return n; } }; class C : public A { // do not contain property n, it nolonger need getN(); }; class A is a abstract class. Now I have class C derived from A. But it dose not like class B has a property n . So I can't overload getN() , and then class C is a abstract class, which I cannot instantiate it. So if I want instantiate class C, what should I do? 回答1:

Running Android Virtual Devices 2.3.3 or 4.3 versions in Mac OS 10.9 halt my system

由 Deadly 提交于 2019-12-25 12:42:42
问题 I've tried to run several times in Mac OS 10.9 and my system halt when I Android emulator starts. I don't know how to solve that problem. The only solution when it happens is switch off my laptop. Any ideas are welcomed. 回答1: Intel released a fix for Mavericks OS X 10.9 on 11/06/2013. https://software.intel.com/en-us/blogs/2013/11/06/intelr-haxm-hot-ffixes-for-os-x-mavericks-109-and-windows-81-available-for Intel(R) Hardware Accelerated Execution Manager (HAXM) Version 1.0.7 Hot fixes for OS

how to convert abstract class to normal class without overload pure virtual function?

由 ◇◆丶佛笑我妖孽 提交于 2019-12-25 12:42:09
问题 look at following code: class A { public: virtual int getN() = 0; }; class B : public A { private: int n = 2; public: int getN() { return n; } }; class C : public A { // do not contain property n, it nolonger need getN(); }; class A is a abstract class. Now I have class C derived from A. But it dose not like class B has a property n . So I can't overload getN() , and then class C is a abstract class, which I cannot instantiate it. So if I want instantiate class C, what should I do? 回答1:

Not defining Virtual method in derived class as well

由 十年热恋 提交于 2019-12-25 07:49:59
问题 I have the following class hierarchy. class A { public: virtual bool foo() const; }; class B : public A { // Redeclare foo as virtual here? }; class C : public B { bool foo() const {/*Definition*/ return true;} }; class D : public B { bool foo() const {/*Definition*/ return false;} }; So the foo() method the class C and D wants to implement, B doesn't. How can I achieve that? Do I have to re-declare the foo() as virtual in class B? Note: Ignore minor syntactical error here and there. This is

Problem in calling a virtual function across Symbian DLLs

由 纵然是瞬间 提交于 2019-12-25 06:28:27
问题 My IM application setup is like below: User Interface module (exe) Plugin module ( A polymorphic DLL that provides an abstract interface for different protocols to the UI module ) Several Protocol DLLs ( Shared library DLLs that implement the respective protocols, like Jabber, ICQ etc ) Now, I was asked to implement contact list caching feature and that meant doing File I/O. Since File I/O cannot be done in the protocol DLLs ( it cannot access the applications private folder ) I implemented a

CakePHP 2.4.4 Unable to sort/order by virtual field with paginate (Paginator)

由 烈酒焚心 提交于 2019-12-25 03:59:22
问题 My Virtual Field for Property model, generated in beforeFind(), called 'distance', works. However, I can't sort by it. I currently have this as part of the search form: echo $this->Form->input('sort', array( 'options' => Hash::get($predefined, 'sort'), // List of options )); Which adds sort to the URL, and it works for all normal fields, but not the virtual field distance. Should I have implemented this differently? As far as I'm aware, Virtual Fields should work fine with pagination. EDIT:

Unable to List File or Directory Contents on ASP.NET Page using Shared Drive

由 你。 提交于 2019-12-25 03:59:21
问题 In this question I'm using Visual Studio 2008. My code is quite simple, as it was used from a reference I grabbed off the web. I'm using ASP/VB.Net, IIS6.0 on a Windows Server 2003 box. I've looked at various sources online, and have not been able to piece together a proper result. The purpose of this is to list a slew of directories and their respective files, and allow the user to eventually manage that directory (such as open and delete files). Here is my ASPX page: <%@ Page Language="vb"

Compute homography for a virtual camera with opencv

由 て烟熏妆下的殇ゞ 提交于 2019-12-24 16:16:37
问题 I have an image of a planar surface, and I want to compute an image warping that gives me a synthetic view of the same planar surface seen from a virtual camera located at another point in the 3d space. So, given an image I1 I want to compute an image I2 that represents the image I1 seen from a virtual camera. In theory, there exists an homography that relates these two images. How do I compute this homography given the camera pose of the virtual camera, as well as it's matrix of internal
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