overriding

Overloading virtual functions of the same name from different base classes. Is it possible? [duplicate]

孤街醉人 提交于 2019-12-01 00:11:08
问题 This question already has answers here : C++ virtual override functions with same name (4 answers) Closed 6 years ago . The title is probably confusing. Suppose we have the following set up; class A { public: virtual void fn() = 0; }; class B { public: virtual int fn() {}; }; class C: public A, public B { }; Is there any way to define A::fn in class C ? 回答1: No . This is not possible. It will always conflict with either of the fn() . The syntax of fn() are different, void fn(); // in A and in

Joomla - Overriding getItem method

有些话、适合烂在心里 提交于 2019-12-01 00:03:15
I want to override the method getItem() found in file \administrator\components\com_content\models\article.php line 257 public function getItem($pk = null) I need to modify the return value based on the value of variable $pk. How do I do this? I am hoping to find a way to not to modify the core. Also, if override is possible, can I make a plugin out of it? Am using Joomla 2.5.9 With some more searching, came across a beautiful solution. All I needed was to override the model (article.php) under com_content. This got it done. Using the Plugin Override plugin the Joomla core can be overridden.

Is it necessary to override == and != operators when overriding the Equals method? (.NET)

和自甴很熟 提交于 2019-11-30 23:50:30
问题 Or it's advisable to do that? Why? 回答1: See the guidelines for overriding Equals() and operator==. Quote: By default, the operator == tests for reference equality by determining whether two references indicate the same object. Therefore, reference types do not have to implement operator == in order to gain this functionality. When a type is immutable, that is, the data that is contained in the instance cannot be changed, overloading operator == to compare value equality instead of reference

Type Composition: overriding interface types

时光怂恿深爱的人放手 提交于 2019-11-30 23:22:01
I want to compose a type of another type, but replace one of the fields (which is an interface value) with a fake. The problem I am getting is the underlying field is being used, so I can't seem to override the field. I've demoed the problem here: https://play.golang.org/p/lHGnyjzIS-Y package main import ( "fmt" ) type Printer interface { Print() } type PrinterService struct {} func (ps PrinterService) Print() { fmt.Println("PrinterService") } type Service struct { Client PrinterService } func (s Service) PrintViaMethod() { s.Client.Print() } type FakeService struct { Service Client Printer }

Class Inheritance/Method Override

[亡魂溺海] 提交于 2019-11-30 23:18:42
This is my first time working with classes, so excuse my ignorance. I have a Pet class that is my base class. I have two children classes, Dog and Cat. What I'm trying to do is have the Cat and Dog methods override the Pet method by saying "Woof!" and "Meow!" instead of speak. Then in another form I have to print the information (name, color, and them speaking) on a button press. class Pet { protected string name, color, food; public string Name { get { return name; } set { name = value; } } public string Color { get { return color; } set { color = value; } } public string Food { get { return

why cant we override a base class method with private extended class method?

孤街浪徒 提交于 2019-11-30 22:54:43
class One { void foo() { } } class Two extends One { private void foo() { /* more code here */ } } Why is the above snippet of code wrong? I'm going to try to incorporate the ideas from the other answers to come up with a single answer. First off, let's take a look at what's going on in the code. A look at the code The One class has a package-private foo method: class One { // The lack of an access modifier means the method is package-private. void foo() { } } The Two class which subclasses the One class, and the foo method is overriden, but has the access modifier private . class Two extends

Java: design interface to force implementations to override toString

左心房为你撑大大i 提交于 2019-11-30 22:26:54
问题 I'm developing an SPI and would like to define a Reportable interface such that any implementations must override toString() to something that is meaningful. Is there any way in Java to write an interface such that any of its concrete implementations must override Object's toString() ? For instance: public interface Reportable { public String toString(); } public class Widget implements Fizz, Buzz, Reportable { // ... @Override public String toString() { // ... } } I know the above code doesn

Incorrect variable names in overridden methods

醉酒当歌 提交于 2019-11-30 22:17:48
When I let Android Studio generate override method it will generate the method with strange parameter names. For instance according to documentation onCheckedChanged should look like this: public void onCheckedChanged(CompoundButton buttonView, boolean isChecked){} but i got public void onCheckedChanged(CompoundButton compoundButton, boolean b){} or onDateSet in DatePickerDialog i got: onDateSet(DatePicker datePicker, int i, int i1, int i2) instead of onDateSet(DatePicker view, int year, int month, int dayOfMonth) I got Android SDK set up in a project and Sources for Android 27 installed. Any

Is method hiding a form of Polymorphism?

拟墨画扇 提交于 2019-11-30 21:40:36
Polymorphism is the ability to take many forms. Method overriding is runtime polymorphism. My questions are: Is there anything like static polymorphism in Java? Can method hiding be considered a form of polymorphism? In this question's answer , it is said that static methods are not polymorphic. What is the reason for that? Evgeniy Dorofeev If we run this test class A { static void x() { System.out.println("A"); } } class B extends A { static void x() { System.out.println("B"); } } class Test { public static void main(String[] args) throws Exception { A a = new B(); a.x(); } } it will print A.

C# Member variable overrides used by base class method

拟墨画扇 提交于 2019-11-30 21:00:29
OK so I admit right off the top that this is a bit screwy … but it does serve a logical purpose. I’m using C# for a current project and I’m trying to find a way to override a member variable in a derived class, but access the overridden variable in a base class method. To make things more “entertaining” it would be preferable if the overridden member variable was static (this is NOT shown in the example code below). Here is my sample code: class baseclass { protected string[] array = null; public string method() { string str = ""; foreach (string x in this.array) { str += x + " "; } return str