Casting and heritage in Java

Consider this simple code: class A {} class B extends A {} public class TestClass { public static void main(String args[]) { A[] a, a1; B[] b; a = new A[10]; a1 = a; b = new B[20]; a = b; // 1 b = (B[]) a; // 2 b = (B[]) a1; // 3 } } Look closely at

Inherit class less some fields - possible workarounds?

I don't have access to the definition of a class but I can inherit from it. I want in the derived class to be denied from accessing some fields that are public in the base class for obvious reasons of accidentally accessing/setting/getting the fields

Entity Framework TPC inheritance problem

I'd like to have Table Per Concrete type inheritance in my application: public class Row { public int Id {get;set;} public string Name {get;set;} } public class ExtendedRow : Row { public int Weight {get;set;} } Each of the classes need to be mapped

Add prototypes from one object to another

Let's say I have object Cat in a node module. I want to replace the Cat function itself and not it's prototypes. To put it another way I want to take the prototoypes from one object and add them to another. function Cat(name, breed){ = name

to call a C ++ parent constructor

Is there any advantage to calling the parent constructor explicitly in the derived class constructor? is this: LockableDoor :: LockableDoor() : Door(), locked_(true) { } is different from this: LockableDoor :: LockableDoor() : locked_(true) { } someh

Multiple inheritance with a base class

(Removed original text as it is unrelated to the current question which has already been answered. See revisions.) Here is my example test.hpp (simplified): class House { private: int nWindows; public: House(int nWindows); int getNumberOfWindows(); }

Name of the design reason: get class level class

Especially in unittests we use this "design pattern" I call "get class from class level" class FrameWorkHttpClient(object): .... class FrameWorkTestCase(unittest.TestCase): # Subclass can control the class which gets u

Get initialization of the base class constructor, a bad habit?

I have a base class in an OpenGL project which represents 3DModel in general. Now I want to create a more specialized class that will inherits from 3DModel. My problem is the mandatory base class constructor call in the initialization list. Is there

Why does my code give me a stackdump error when I run it?

We are supposed to make classes of animals which inherit from classes of different types of animals, i.e the Dog class will inherit from the Carnivore class which will inherit from the Mammal class. I have tried using my classes in my own main functi

C ++ Two child classes share a variable from their base class

So say I have 3 classes: Base, A, and B. Base is a base class for both class A and class B. Base has a variable val that A and B can access. How would I get it to work where I can set the val variable through class A, and it is reflected in class B?

Access to type-specific methods & ldquo; class, in a collection

Situation: I have an abstract class with several methods: I have a few sub classes that extend the class above I have a collection <MyAbstractClass> collection filled with new objects of the sub classes in my main class I have a unique method of one

Inheritance in c ++ with model class error

I´m new to c++. i´m getting an error "Symbol 'List' could not be resolved" I´m working on eclipse i can´t figure out what is the problem... List.h here is the declaration of the father class which is a generic class, which Vector will inherit #i

How to use the Singleton model via inheritance?

I am trying to use the Singleton design pattern via my abstract Charcter class so all sub classes can acces the object instance. Here is my singleton class: class GatewayAccess { private static GatewayAccess ph; // Constructor is 'protected' protecte

C # Covariance on the types of subclass return

Does anyone know why covariant return types are not supported in C#? Even when attempting to use an interface, the compiler complains that it is not allowed. See the following example. class Order { private Guid? _id; private String _productName; pri

@XmlSeeAlso alternative

I have the following: class A{ @XmlElement String name; //getters and setters } and class B extends A{ @XmlElement String height; //getters and setters } finally I have @XmlRootElement class P{ @XmlElement List<A> things; //getters and setters } If

PHP - Object Mixing Injection & amp; heritage

This is a follow up question on the following answer : Parent Object in php class A { protected function doSomeStuff(){ echo 'a method that all children will need to call'; } } class B { protected $_parent; public function __construct($parent) { $thi

create objects from a model class with a different type

I was not really sure how to formulate my question, but here is the puzzle I am trying to resolve: if (config.a) myObject = new Object<DummyInterface>(); else myObject = new Object<RealInterface>(); so the task is to create a object with a dum

How is U [] castable in T []?

It is clear that the T[] array type is not covariant as the elements of a T[] can be set by index. And yet, a U[] can be cast to a T[] without any complaints from the compiler as long as U derives from T. Man[] men = new[] { new Man("Aaron"), ne

What exactly does the execution polymorphism mean?

I'm slightly confused about runtime polymorphism. Correct me if I am wrong, but to my knowledge, runtime polymorphism means that function definitions will get resolved at runtime. Take this example: class a { a(); ~a(); void baseclass(); } class b: c

Semi-inheritance in C: How does this extract work?

One way to hack limited form of polymorphism in C is to do something like this: typedef struct { int x; } base; typedef struct { base super; int y; } derived; Now you can refer to a derived instance as a base instance, depending on how the variable i

Java: How to access a two-level parent class method?

I have a class that extends a class that I need to overide, but I need to call that class's parent class. since I can't call super since that will execute the direct parent what is the best way to get the parent of my parent class? I am sure this is

Inheritance in Python

We just started learning about class inheritance and attribute lookup in python. I have a question about the following code: class a : n = 1 class b : n = 2 class c : n = 3 class d (a,b) : pass class e (d,c) : pass I know that e.n would equal 1 due t

Complex mapping of NHibernate components

EDIT: I simplified the problem to leave only what really bothers me. Hello all, I am trying to make the following mapping. In my database, I have a table called "ReportRowValue" containg the following columns: RowNumber ColumnNumber StringValue