overriding

I'd like override one mutable variable in Trait in constructor. But it will complain that "overriding variable a in trait A of type Int; variable a cannot override a mutable variable". Why the scala do not allow me do that ? And any best practise for this ? Thanks trait A{ var a:Int = _ } class B(override var a:Int) extends A You cannot override it (for reasons that don't reveal themselves to me right now, except, that vars can be modified anyway so why override them), but you can leave the declared variable uninitialised and delegate the latter to B : trait A { var a: Int } class B(var a: Int

public class Foo { public int a = 3; public void addFive(){ a += 5; System.out.print("f "); } } public class Bar extends Foo { public int a = 8; public void addFive(){ this.a += 5; System.out.print("b " ); } } public class Test { public static void main(String args[]){ Foo f = new Bar(); f.addFive(); System.out.println(f.a); } } I am getting output b 3 .why it is not giving b13 as output.Can anyone please explain. Aravind R. Yarram Assuming class Foo is declared as below class Foo { public int a = 3; public void addFive() { a += 5; System.out.print("f "); } } Variables have no concept of

I am implementing Key Navigation for an application and I want to override the space key functionality when a Combo Box is focused such that it acts like an enter key; like this: if (!cb.IsDropDownOpen) { cb.IsDropDownOpen = true; } else { cb.SelectedItem = cb.{non-public member HighlightedItem}; cb.IsDropDownOpen = false; } The problem is that I need to get the value of that non-public member so that I can set the selected value and close the drop-down (how enter would normally work). Now the question is: What is the fastest and hassle free way of achieving this? You'd have to use reflection

When should one do the following? class Foo : Control { protected override void OnClick(EventArgs e) { // new code here } } As opposed to this? class Foo : Control { public Foo() { this.Click += new EventHandler(Clicked); } private void Clicked(object sender, EventArgs e) { // code } } Overriding rather than attaching a delegate will result in more efficient code, so it is generally recommended that you always do this where possible. For more information see this MSDN article . Here is a pertinent quote: The protected OnEventName method also allows derived classes to override the event without

I stumbled upon this piece of code. I tried to guess what will be the result of running it before actually doing so. I was really confused when I saw them & in need of some explanations. This is the code: public class A { String bar = "A.bar"; A() { foo(); } public void foo() { System.out.println("A.foo(): bar = " + bar); } } public class B extends A { String bar = "B.bar"; B() { foo(); } public void foo() { System.out.println("B.foo(): bar = " + bar); } } public class C { public static void main(String[] args) { A a = new B(); System.out.println("a.bar = " + a.bar); a.foo(); } } The output is

using namespace std; #include <cstdio> #include <iostream> class One{ private: virtual void func(){ cout<<"bark!"<<endl; } }; class Two: public One{ public: void func(){ cout<<"two!"<<endl; } }; int main(){ One *o = new Two(); o->func(); } Why is there an error on o->func() ? I don't know the mechanism behind it... In my opinion, o->func() should call the func() in the derived class, which is public, so there wouldn't be problems, but it says: error: ‘virtual void One::func()’ is private Accessibility check is performed based on the static type of the object. The type of o is One* . This means

I'm trying to figure out how to override the dataGridHeader style defined in DataGrid.css ! GWT core. The GWT style name is obfuscated with adler32 so I can't simply use .dataGridHeader in my css. In my case I wish a simple change of white-space:normal. I've seen may articles here about injecting css but they all appear to be class level rather than a sub style used within a component like DataGrid. How do I override a header style used within a component like DataGrid? Just like with any ClientBundle and CssResource : create an interface that extends Datagrid.Resources and overrides the

I have a repository for one of my projects that has a nested repository using the svn:externals property to update files from an external library. The problem is that I need to comment out one of the function declarations from one of the headers in this library, and carry around the modified header with the root repository. Is there a way that this could be done, so that when the library is updated, it overrides that specific file with my version of it? What you want sounds like a "vendor branch" scenario to me. current repository root |-- myproject | -- mycode | -- library -> svn:externals to

I have the extension CreativeStyle CheckoutByAmazon installed on my magento 1.7 store and I am trying to override the CheckoutController Class but magento seems to ignore my override. Any suggestions will be much appreciated. Also cleared cache but still doesnt work (In app/code/local Folder) MyModule \CheckoutByAmazon \controllers \CheckoutController.php \etc \config.xml (app/etc/config.xml) <?xml version="1.0" encoding="UTF-8"?> <config> <modules> <MyModule_CheckoutByAmazon> <version>0.1.0</version> </MyModule_CheckoutByAmazon> </modules> <frontend> <routers> <checkoutbyamazon> <args>

I would like to have my own implementation of the toString() method for an ArrayList in Java. However, I can't get it working even though I added my toString() like this to the class that contains the ArrayList. @Override public String toString() { String result = "+"; for (int i = 0; i < list.size(); i++) { result += " " + list.get(i); } return result; } When I call my ArrayList like this list.toString() , I still get the default representation. Am I missing something? You should do something like public static String listToString(List<?> list) { String result = "+"; for (int i = 0; i < list