overriding

问题 base class class Drawer { public abstract void Draw<T>(T type); } derived class #1 class ADrawer : Drawer { public override void Draw<T>(List<T> list) { foreach (var a in list) { DrawA(a); } } public void DrawA(Agent a) { //draw code here } } derived class #2 class AnotherDrawer : Drawer { public override void Draw<T>(T number) { if (number == 1) { //draw code } } } The error is in the #1 derived class : "no suitable method found to override" Should I be using 'virtual' in the base class as

问题 Here is an example of what I am looking to do. public class A { public virtual void DoSomething(string a) { // perform something } } public class B : A { public Override void DoSomething(string a, string b) { // perform something slightly different using both strings } } So I want to override DoSomething from class A and allow it to pass a second parameter. Is this possible? 回答1: When overriding a virtual method, you must keep the original "contract" of the method, which in your case is a

问题 I have this code : class Event{}; class CustomEvent:public Event{}; class Handler { public: virtual void inform(Event e ){} }; class CustomHandler : public Handler { public: void inform(CustomEvent e){} }; CustomEvent cEvent; Handler* handler = new CustomHandler; //this calls Handler::inform(Event), not CustomHandler::(CustomEvent) , as I expected handler->inform(cEvent); If I change the code to this : class Handler { public: virtual void inform(Event e ){} virtual void inform(CustomEvent e){

问题 Basically, I want the C# compiler functionality of its override keyword in my C++ code. class Base { virtual int foo(int) const; }; class Derived : public Base { virtual int foo(int); // wanted to override Base, but forgot to declare it const }; As we all know, the above code will compile fine, but yield some strange runtime behavior. I would love my C++ compiler to catch my poor implementation with something like C#'s override keyword. Are there any keywords like "override" being introduced

问题 If I have a list of objects, I can use the __cmp__ method to override objects are compared. This affects how the == operator works, and the item in list function. However, it doesn't seem to affect the item in set function - I'm wondering how I can change the MyClass object so that I can override the behaviour how the set compares items. For example, I would like to create an object that returns True in the three print statements at the bottom. At the moment, the last print statement returns

问题 public abstract class A { public void CallMe() { Console.WriteLine("I am A."); } } public class B : A { new public void CallMe() { Console.WriteLine("I am B."); } } class Program { static void Main(string[] args) { A a = new B(); a.CallMe(); } } output is "I am A." Why this happening? Is this reasonable? compiled by Visual Studio 2012. 回答1: You need to make the CallMe() method in your base class virtual and then use the override modifier in B : public abstract class A { public virtual void

问题 Here's the c# code I'm trying to compile Fairly simple, testDMO that inherits from testDMOBase Then test that inherits from testBase public abstract class testDMOBase { } public class testDMO : testDMOBase { } public abstract class testBase { abstract protected void LoadCRUD(testDMOBase dmo); } public class test : testBase { override protected void LoadCRUD(testDMO dmo) { } } I'm getting the following errors: 'test' does not implement inherited abstract member 'testBase.LoadCRUD(testDMOBase)'

问题 I'm using the System.Diagnostics.Process class to execute a command line program. I am using the OutputDataReceived method to redirect the output to my own method. pr.OutputDataReceived += new DataReceivedEventHandler(OnDataReceived); pr.ErrorDataReceived += new DataReceivedEventHandler(OnDataReceived); However, I have multiple Threads running multiple instances of this cmd program. What I want to do is to be able to identify which process instance the output data came from - ideally, a

问题 I have an application, that uses the MultiSelectionModel, and it works great, but I need the site I'm developing to work on mobile devices, and so I can't use the keyboard to assist in selecting the elements (since it doesn't exist). EX: On the desktop I just hold ctrl and click on all the element that I want to select. So on the mobile device, I would like to modify the default behavior of the MultiSelectionModel so that when you click on a CellList item, it toggles the selection state of

问题 There is a cherry-pick command in the git which allows me to copy some commit on top of the current. However, it does some conflict resolution, that I do not care about. What is alternative to cherry-pick which just copies picked commit over on top of current commit? I can do it manually: select desired commit, copy its files, save them into non-managed folder, select current commit which will be the base for new one, copy the archived files into the git working folder. Separately, I have to