Inheritance is a way to reuse code of existing objects, or to establish a subtype from an existing object, or both, depending upon programming language support.

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2
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3answers
209 views

Inheritance: Is code from superclass virtually *copied* to subclass, or is it *referred-to by subclass*?

Class Sub is a subclass of class Sup. What does that mean practically? Or in other words, what is the practical meaning of "inheritance"? Option 1: The code from Sup is virtually copied to Sub. (as ...
0
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1answer
128 views

Should I use inheritance or an interface?

So in a nutshell I have an abstract class : public abstract class Member { public string PCode { get; set; } public string Reference { get; set; } public DateTime? ElectedDate { get; set; } } And ...
4
votes
3answers
445 views

What is the process of determining which method in a class hierarchy should execute known as?

I thought I understood inheritance and polymorphism, but I was given this question, and I can't, for the life of me, figure out what the proper answer is or what they're trying to get at: The ...
2
votes
2answers
147 views

Testing abstract class' behavior

I'm currently refactoring an existing design, which was created without TDD. There is a class hierarchy with one abstract base class and two subclasses. In the original design, these classes were ...
-2
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0answers
33 views

Application of Composition Inheritance and Interfaces A Model [closed]

For learing oop I opend a little project by myself. I like rollplaying so I choose to build a character generator. I guess it is quite similar to a online game character generator. I cannot explain ...
-4
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0answers
55 views

How to explain Inheritance and Polymorphism to NON CS Students with examples? [closed]

I was wondering if some one could help me with explaining Inheritance and Polymorphism with real world examples to NON CS students preparing for a job interview in a IT firm. PS: My first question on ...
1
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2answers
64 views

Inheritance vs 'specification' by fields

I'm currently reading 'Head first design patterns', and already the first chapter threw some questions towards me. This chapter introduces the 'prefer composition over inheritance' design principle, ...
0
votes
1answer
87 views

When is it suitable to use inheritance [duplicate]

I recently had a small "argument" about inheritance with a friend. I think people overuse it a lot. Intuition tells me that that the only good reason for class inheritance is polymorphism - when there ...
0
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0answers
25 views

subclass QAbstractTableModel - reuse as much code as possible

in my PyQt application I am heavily using the model/view approach. For every model I create, I do the following: class myModel(QtCore.QAbstractTableModel): def __init__(self, parent = None): ...
1
vote
2answers
116 views

Alternatives to inheritance on complex structures?

I'm working on an ASP.NET Webforms project, using the MVP Pattern (which the presenters as you may know use a Page Controller pattern). I'm given a rather complex inheritance chain for my controllers. ...
1
vote
3answers
212 views

Why are inheritance and interfaces restricted to instance members?

Disclaimer: I think the rules are almost the same in most OO languages, but since I'm most familiar with C# I'll be relating to this specific language. I think that the use of attributes and ...
3
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3answers
109 views

Why should one subclass instead of composite when using the Factory Method design pattern?

I'm currently learning about design patterns. I learned about the Factory Method pattern. This pattern means that in order to implement a factory to create objects, one should subclass the class that ...
1
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3answers
424 views

Should utility base classes be avoided

Knowing that C# doesn't support multiple inheritance, is it considered bad form to write a utility base class? Some initial thoughts: I could create an interface and a concretion, but then the ...
1
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5answers
143 views

Clarification about Polymorphism / Inheritance

I am trying to better my understanding of polymorphism. Say I have a base class called baseClass with one method called foo() and I have three derived classes called derived1 , derived2 and derived3 ...
-1
votes
1answer
30 views

Concerning JavaScript prototype and the initial constructor function

I am going through a tutorial on OOP in JavaScript (javascriptissexy.com using OOP in JS: What you Need to know). The instructor is explaining the Constructor/Prototype pattern of object creation. I ...
1
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1answer
119 views

inheritance and static final variables

I'm a programing student. I've been having problem to organize Java classes that use inheritance and static final variables. Let say I have an abstract class named Form that has two children named ...
0
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0answers
52 views

Changing method signature for implementing classes in PHP

Is there any decent work around to PHP's lack of Generics that allow static code inspection to detect type consistency? I have an abstract class, that I want to sub-class and also enforce that one of ...
0
votes
1answer
49 views

Would it make sense to add parameters of an inferred type to inheritance?

I'll write this in PHP (where this thought originated), but this is generic to any object-orientated language. Basically, this is an addition to abstract classes that defines the implementation of its ...
0
votes
1answer
174 views

Can we say that Java or C# have unified inheritance trees?

Can we say that Java or C# are OO languages with a unified inheritance tree/unified type system? By unified inheritance tree/unified type system I mean that every class derives implicitly or ...
3
votes
3answers
373 views

Why is inheritance only defined at compile-time?

I found this statement from the gang of four's "Design Patterns" particularly odd; for some context, the authors are comparing inheritance versus composition as reuse mechanisms [p. 19]: "...you ...
2
votes
1answer
76 views

Refactor an old model of a LastUser Modification on every Object?

I have a software requirement, that needs to store the user that made the last modification to another object, for every object (assume that all objects are already mapped and into a BD). So we have ...
0
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0answers
46 views

How to understand codebase of complex opensource application [duplicate]

I'm trying to develop a new feature for open source application. But the existing application uses different APIs like Qt and KDE3. And more over the existing files are also very complexand depend on ...
2
votes
1answer
139 views

Using partially implemented interfaces

Consider the following hierarchy in C++ notation: class A { public: virtual void doStuff()=0; virtual void doOtherStuff()=0; }; class B:public A { public: ...
0
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1answer
105 views

block access to area/controller's methods but allow inherited controller to run methods, asp .net mvc5

I am trying to find out how to block a whole area/controller from being accessed by typing url website.com/area1/basecontroller/method1 (this area also contains the views that will be displayed) , ...
3
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2answers
194 views

Help with inheritance hierarchy design

I'm having trouble designing an inheritance hierarchy. In the figure: Base class: This uses the Template Method. Contains core logic/algorithm that calls virtual/abstract methods Derived ...
2
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1answer
133 views

Inheritance in test classes

I have an interface Serializer with methods serialize and isSerializerFor. I created a first implementation of this using TDD, and ended up with a nice clean test case fully covering a nice clean ...
3
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2answers
179 views

which pattern to use - if at all

I am fairly new to using patterns and although I understand some of them to a point I find it difficult to work out which one(s) to use in a particular situation. I am trying to wrap up an existing ...
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2answers
109 views

What are some examples of inverted classical inheritance? [closed]

Are there any examples of inheritance in languages where classes call their subclasses' methods rather than their super classes' methods? It should not behave like traditional inheritance like the ...
3
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1answer
56 views

Specific and generic behaviour for derived objects that client doesn't need to be aware of

We have a database with tables that use an inheritance hierarchy. An entity in the derived table will have an ID that matches an entity in the base table and so on through the hierarchy. We have ...
3
votes
2answers
274 views

Base class should have no knowledge of its subtypes?

What's the OO principle that states (in sum): A base object should have no knowledge of its subtypes. I thought it was Liskov Substitution but after reading that wikipedia article I don't ...
32
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3answers
1k views

Does Java development typically involve more subclassing than C#/.NET?

I've recently started looking at Android development. This has brought me back into the world of Java software development. The last time I worked with Java, I'll admit, I didn't understand OOP nearly ...
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5answers
166 views

shall a vector2 extends a vector3 or is it the opposite?

Perhaps the question might be tied to a theoritical or mathematical forum, but since it is for programming purpose, i ask here first: In a computer vision context, i write a couple of interfaces ...
48
votes
9answers
3k views

Is there any “real” reason multiple inheritance is hated? [closed]

I've always liked the idea of having multiple inheritance supported in a language. Most often though it's intentionally forgone, and the supposed "replacement" is interfaces. Interfaces simply do ...
11
votes
12answers
2k views

Is “If a method is re-used without changes, put the method in a base class, else create an interface” a good rule-of-thumb?

A colleague of mine came up with a rule-of-thumb for choosing between creating a base class or an interface. He says: Imagine every new method that you are about to implement. For each of them, ...
2
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4answers
485 views

Confusion about inheritance

I know I might get downvoted for this, but I'm really curious. I was taught that inheritance is a very powerful polymorphism tool, but I can't seem to use it well in real cases. So far, I can only ...
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1answer
49 views

Convention for using super class functions and members

Is there a Convention or common way for using super class functions and members? For example the super class has the function protected void Foo() and protected int myInt; In subclass would I want ...
3
votes
4answers
505 views

Are trivial protected getters blatant overkill?

Something I really have not thought about before (AS3 syntax): private var m_obj:Object; protected function get obj():Object { return m_obj; } private var m_str:String; protected function get ...
0
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2answers
262 views

Object inheritance and method parameters/return types - Please check my logic

I'm preparing for a test and doing practice questions, this one in particular I am unsure I did correctly: We are given a very simple UML diagram to demonstrate inheritance: I hope this is clear, it ...
1
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1answer
83 views

Inherit one instance variable from the global scope

I'm using Curses to create a command line GUI with Ruby. Everything's going well, but I have hit a slight snag. I don't think Curses knowledge (esoteric to be fair) is required to answer this ...
3
votes
5answers
1k views

Why we use virtual and override keywords in c#

Can anyone explain me what's the point of overriding base class implementations (if its not abstract), because it's not ethical move to modify features of the parent class according to the wishes of ...
0
votes
2answers
156 views

Python — when should a class have-a rather than be-a?

This is related to "Extends is evil" vs. OCP? but separate because the idea of "implement the interface" doesn't exist in Python. I'm writing a class to pull some data off a webpage. It's ...
5
votes
9answers
921 views

How can designing for inheritance cause extra cost? [closed]

So I wanted to inherit from a sealed class in csharp and got burned. There is just no way to unseal it unless you have access to the source. Then it got me thinking "why sealed even exists?". 4 ...
0
votes
1answer
154 views

Will having ClassA extend ClassB slow down my runtime performance compared to having classC which contains all the members of ClassC?

I have a class with a lot of methods. I would like to group similar methods together in their own class, but all of the methods need to extend another class, ClassC. So I was thinking of having ...
0
votes
6answers
549 views

What are the reasons to create UIView subclass?

I've noticed that there are a lot of UIView subclasses in my legacy project. Mostly the only reason of such a subclass is to split bigger view into custom subviews and provide layout for its subviews ...
5
votes
4answers
677 views

Can a method that must be overridden be considered private?

Suppose I have a class C with a method f() which is meant to be used only within C's implementation, but which should be overridden by C's subclasses. Is it reasonable, or "pythonic", to consider it ...
3
votes
3answers
159 views

Which one subsumes the other: class-based object-orientation or prototypal inheritance?

In this talk: http://www.youtube.com/watch?v=hQVTIJBZook, Douglas Crockford claims that class-based object-orientation can be represented in terms of prototypal inheritance. The construction he gives ...
4
votes
1answer
265 views

Is using protected inheritance to hide (but exploit) implemented interface from the public ok?

Recently, we had a discussion about code using protected inheritance in order to hide the fact (to client code) a class inherits from a specific base class but to exploit this fact in the ...
1
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1answer
159 views

Internal exposure of implementation details on inheritance

I'm reading the "Effective Java" book which suggests to favor composition over inheritance. The example it gives shows something like this: public class InstrumentedHashSet<E> extends ...
1
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4answers
461 views

Explanation of the definition of interface inheritance as described in GoF book

I am reading the first chapter of the Gof book. Section 1.6 discusses about class vs interface inheritance: Class versus Interface Inheritance It's important to understand the difference between ...
2
votes
3answers
1k views

Java class to enforce an implementation of super classes' public methods

I have the following : public Class A { public void methodA() { .... } public void methodB() { .... } } I don't have control over Class A. I would like to create ...