hi all i am new in objective c and want to get know about inheritance ... I am aware of all concepts but confused withe the methods that programmer used to inherit a class.... Let i explain my problem.... suppose i have two classes class A and class B... and i want to make B child of A.... for that sometimes programmer used #import "c...
How does Virtual Method Invocation work in C++? ...
Say I have classes declared like this: public abstract class IdentifiableEntity { public boolean validate() { return true; } } public class PreferenceCategory extends IdentifiableEntity { public boolean validate() { return true; } } Now, let's say I have PreferenceCategory variable created, and I want...
Hi! I have an inheritance hierarchy with overlap. The system knows about People that can be Clients, Providers and Agents. A person have to belong to one of these classes but can belong to two or three, i.e. one Person can be a Client and a Provider at the same time. In the database I think that the problem is solved, one table per clas...
Is it possible to extend the Math class and still use the Math class to call the extended method? For example, I have a method public static double mean (LinkedList<? extends Number) I would like to call like this Math.mean(list). Is this doable? How? Thanks. ...
I'm attempting to write a java program that initializes certain layouts based on what the user selects. What I want to do is try to avoid writing a bunch of if-statements so the code can be scalable for future use if more layouts need to be added. I heard the best way to implement this is using polymorphism but my understanding of polymo...
I'm sorry if this is an old issue or a known problem, but I haven't been able to find an answer online. If I have the code <style> html, body { height: 100%; width: 100%;} #div1 {height:50%; min-height:200px;background-color:red;} #div2 {height:100%; background-color:black;} </style> <body> <div id="div1"><div id="div2"></di...
Suppose I have a base and derived class: class Base { public: virtual void Do(); } class Derived:Base { public: virtual void Do(); } int main() { Derived sth; sth.Do(); // calls Derived::Do OK sth.Base::Do(); // ERROR; not calls Based::Do } as seen I wish to access Base::Do through Derived. I get a compi...
For instance I have code like that class Base1 { virtual void wonderFULL() = 0; }; class Base2 { // all this weird members }; class Derived : public Base1, public Base2 { // not so weird members }; int main() { Derived Wonder; magicFunction(&Wonder); return 0; } void magicFunction(Base2 *ptr) { if (Base1 *b1 = dynamic_...
Basically everyone writing about member enumeration in JavaScript heavily advocates the use of the hasOwnProperty method as to avoid going up the prototype-chain. I understand that this is a form of defensive programming as to prevent iterating over members that are added, for example, to the Object.prototype. But what about the other...
I have a simple C++ base class, derived class example. // Base.hpp #pragma once class Base { public: virtual float getData(); virtual void setData(float a, float b); virtual void setData(float d); protected: float data; }; //Base.cpp #include "stdafx.h" #include "Base.hpp" float Base::getData() { return data; ...
I'm seeing a very strange problem when overriding an abstract method and trying to call the base class's method that I'm currently overriding. //In Dll "A" namespace Rhino.Etl.Core.Operations { using System; using System.Collections; using System.Collections.Generic; public class Row {} public interface IOperation ...
If I have a generic class like this: public class Repository<T> { public string Greeting(T t) { return "Hi, I'm " + t.ToString(); } } which is extended like this: public class FooRepository : Repository<Foo> If FooRepository has a method called Greeting(Foo foo), does that method have the same signature as the base class ...
Hi, i have 2 classes A and B that extends A. A has a public property and i want that on the instances of B that property can't be accessible. I try to explain better: class A { public $prop; } class B extends A { ... } $instance=new B; $instance->prop; //This must throw an error like "Undefined property prop" I tried with the ...
Has: @MappedSuperclass class Superclass { @Id @Column(name = "id") protected long id; @Column(name="field") private long field; } and @Entity class Subclass extends Superclass { } How to annotate inherited id with @GeneratedValue and field with @Index within Subclass? ...
I have a program that needs to be developed. For confidentiality, I will use vague terms. I have a widget which contains members shared by several different classes. My will handle a widget at 2 stages. each stage has different members but they do share some members as well. This is a diagram of the structure. Widget(...
When making a custom widget in pygtk, what class should it inherit from? I want to be able to put the widget inside other widgets, but I don't want other people to put stuff in mine. Usually I make my widgets inherit from gtk.HBox or gtk.VBox, and that works fine, but it is possible then for someone to do a pack_start() on my widget and ...
Hi there, Is it possible to have "table per type" inheritance in the Entity Framework 4 if the derived table has a composite primary key? Here is my table setup: TABLE: ConfigurationKey (Base Entity) PK: Id TABLE: ConfigurationKey_Device (Derived Entity) PK: ConfigurationKeyId (FK to ConfigurationKey.Id) PK: DeviceId (FK to Device.Id...
I am trying to implement a leftist tree using heaps as a base class. The following is the contents of heap.h: template <class T> class heap { public: virtual void init(T*) = 0; virtual void insert(T*) = 0; virtual T delete_min() = 0; }; The following is the contents of leftist.cpp: #include "heap.h" template <class T> c...
Possible Duplicate: What are the differences between struct and class in C++ http://www.cplusplus.com/reference/std/typeinfo/type_info/ I guess my "teacher" didn't tell me a lot about the differences between struct and classes in C++. I read in some other question that concerning inheritance, struct are public by default... ...