derived-class

问题 I am wondering if there is a way to do this. I create a Qt Application (using Creator 3.6.1, Qt 5.6.0). I add a widget to the main window. For example a QGraphicsView called myView. I create a C++ class derived from QGraphicsView (called DerivedView) code of DerivedView class: class DerivedView : public QGraphicsView { ... I would like my new DerivedView class to control this widget. I can access a pointer to the object through ui->myView. Is there any way to do get my derived class to work

问题 Is there any way to, in a Java derived class, "disable" a method and/or field that is otherwise inherited from a base class? For example, say you have a Shape base class that has a rotate() method. You also have various types derived from the Shape class: Square , Circle , UpwardArrow , etc. Shape has a rotate() method. But I don't want rotate() to be available to the users of Circle , because it's pointless, or users of UpwardArrow , because I don't want UpwardArrow to be able to rotate. 回答1

问题 How to stop the class to be inherited by other class. 回答1: C++11 solution In C++11, you can seal a class by using final keyword in the definition as: class A final //note final keyword is used after the class name { //... }; class B : public A //error - because class A is marked final (sealed). { // so A cannot be derived from. //... }; To know the other uses of final, see my answer here: What is the purpose of the "final" keyword in C++11 for functions? C++03 solution Bjarne Stroustrup's

问题 How to stop the class to be inherited by other class. 回答1: C++11 solution In C++11, you can seal a class by using final keyword in the definition as: class A final //note final keyword is used after the class name { //... }; class B : public A //error - because class A is marked final (sealed). { // so A cannot be derived from. //... }; To know the other uses of final, see my answer here: What is the purpose of the "final" keyword in C++11 for functions? C++03 solution Bjarne Stroustrup's

问题 public class SuperCar: Car { public bool SuperWheels { get {return true; } } } public class Car { public bool HasSteeringWheel { get {return true;} } } How can I set the base class for the derived Supercar? For example, I want to simply set SuperCars base class like this: public void SetCar( Car car ) { SuperCar scar = new SuperCar(); car.Base = car; } Basically, if I have Car objects, I do not want to manually iterate through every property of the car in order to setup the SuperCar oject,

问题 I have a recursive class, a kind of tree, that has instances of itself as member variables. For example: template<class T> class Tree { public: /* Constructors, etc. */ protected: T m_value; Tree<T> *leftChild; Tree<T> *rightChild; }; If I want to add a method that prints all the values using an in-order traversal, I could do this: template <class T> void Tree<T>::printInOrder() { leftChild->printInOrder(); std::cout << m_value << std::endl; rightChild->printInOrder(); } But what if, for

问题 I have a ManagerClass that manages classes that derive from an abstract BaseClass. I need it so that only the ManageClass can access certain methods on the BaseClass. I also need certain methods to be accessible outside the scope of the ManagerClass. Since C# doesn't have friends, I'm encapsulating the BaseClass inside the ManagerClass. The problem: BaseClass is not accessible to derive from Making BaseClass public,means allowing DoStuff() and DoOtherStuff() to be called from outside the

问题 I'm trying to serialize an object to an XML file, but am getting the above error. The problem seems to be with objects that contain a list of a base class but is populated by objects derived from the base class. Example code is as follows: public class myObject { public myObject() { this.list.Add(new Sw()); } public List<Units> list = new List<Units>(); } public class Units { public Units() { } } public class Sw : Units { public Sw(); { } public void main() { myObject myObject = new myObject(

问题 So I want to override the pure abstract method in my derived classes but I got this error. Can someone help me see what happened and how can I complete it. My Device class; class Device { public: Device(); Device(const Device& orig); virtual ~Device(); virtual Device Clone() = 0; } And my derived class; class Radar : public Device { public: Radar(); // Radar(const Radar& orig); // commenting so the compiler using its default copy constructor virtual ~Radar(); Radar Clone(); }; Source file for

问题 How can i pass a list which is a list of DerivedObjects where the Method is expecting a list of BaseObjects. I am converting the list .ToList<BaseClass>() and am wondering if there is a better way. My second problem is the syntax is incorrect. I am trying to pass the list byref and i am getting an error: 'ref' argument is not classified as a variable How can I fix these two problem? thanks. public class BaseClass { } public class DerivedClass : BaseClass { } class Program { static void Main