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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1answer
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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 ...
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1answer
228 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 ...
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0answers
185 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
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1answer
54 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
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1answer
193 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 ...
2
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3answers
600 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
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2answers
122 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
47 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
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1answer
149 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: ...
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2answers
181 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
239 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 ...
4
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1answer
234 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
183 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
119 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
64 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
283 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 ...
33
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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 ...
1
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5answers
169 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 ...
68
votes
9answers
5k views

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

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 ...
10
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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
497 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
51 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 ...
4
votes
4answers
544 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 ...
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2answers
408 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 ...
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1answer
94 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
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5answers
4k 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 ...
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2answers
164 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
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9answers
1k 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
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1answer
171 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 ...
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6answers
1k 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 ...
4
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4answers
1k 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
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3answers
170 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
295 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 ...
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1answer
260 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 ...
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4answers
550 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
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3answers
2k 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 ...
2
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1answer
2k views

Adding base-class (inherited) functionality to classes that you don't control

I have a set of classes from a 3rd party library. These classes use an inheritance structure to share logic. I would like to add a layer of abstraction in the middle of their inheritance tree to add ...
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3answers
329 views

Does non-virtual-by-default lead us to composition-over-inheritance?

There are some design guidelines about testable code in “The Art of Unit Testing”. The first one is “Make methods virtual by default”. I’m curious to know your idea about non-virtual-by-default ...
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3answers
2k views

What is good practice when inheriting static classes isn't possible/allowed

I am developing a project in C# and due to a design decision it is not possible to have a static class inherit another static class. But I have, in my opinion, a case where this would make sense. I ...
0
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1answer
117 views

Refactoring classes with ref to themselves

How can I refactor this code? class Node { public Node Parent { get; set; } } class AVLNode { public AVLNode Parent { get; set; } } I tried to use inheritance, but then I have to use type ...
2
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5answers
495 views

OOP concept: is it possible to update the class of an instantiated object?

I am trying to write a simple program that should allow a user to save and display sets of heterogeneous, but somehow related data. For clarity sake, I will use a representative example of vehicles. ...
13
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3answers
1k views

Is there a specific name for the “Square inherits from Rectangle” paradox?

A certain failure of OOP is shown with a class Square inheriting from Rectangle, where logically Square is a specialization of Rectangle and should therefore inherit from it, but everything falls ...
3
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4answers
420 views

Initializing derived classes in the same way

I have a class Base that has several children, say A, B, C. For testing purposes I'd like to mock those derived classes by deriving from them. So MockA derives from A, MockB derives from B and so on. ...
7
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2answers
395 views

Why is the use of constructors discouraged when creating prototypes?

Quick background: In JavaScript, the constructor function for each object type has a prototype property. The prototype refers to an object that each constructed object uses as the next step up in its ...
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6answers
13k views

Why are constructors not inherited?

I am confused as to what the problems could be if a constructor was inherited from a base class. Cpp Primer Plus says, Constructors are different from other class methods in that they create ...
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2answers
374 views

What principle of OOAD is this pattern breaking?

I'm trying to make a case for not putting the structure in the parent BaseModule class I've shown below. I'm more for a Strategy Pattern, and minimizing inheritance in favor of has-a relationships, ...
7
votes
2answers
515 views

How do I avoid writing lots of pass-through functions in a wrapper?

I have a class, which wraps another class of a common base type. Because the base type interface is quite large this involves writing a lot of pass-through functions. I am looking for a way to avoid ...
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0answers
105 views

Inheritance and constricted referencing

Let's say I have BaseA and BaseB classes. BaseB can have to several references of BaseA instances. Now, we have two other classes, DerivedA and DerivedB that respectively inherit from BaseA and BaseB. ...
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1answer
231 views

Class table inheritance… To 'type' or not to 'type'

I currently have a database that uses Class table inheritance model. Three different tables inherit from this table. The child tables have all a FK to the parent table and the fields are properly ...
3
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2answers
727 views

Tricky compareTo, inheritance, easy to extend - Java

Let's say we have 4 classes A, B, C, D where: A is a superclass of both B and C and C is a superclass of D. I suppose, in a diagram, it should look like this: A / \ B C \ D ...