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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79 views

Base Class vs Common Member Class

Imagine I have two classes like this... public class SingleplayerGameSetup { public int Seed { get; private set; } public int AiNations { get; private set; } } public class ...
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2answers
52 views

Refactoring to an inheritance hierarchy early on

I am building a management tool for recipes. Recipes have a bunch of data, including very generic stuff like an ID, tags, ratings and trivia. I currently only manage recipes, but i want to add support ...
4
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5answers
367 views

Is “too much methods” a valid reason to break the “composition over inheritance” rule?

I usually prefer to follow "composition over inheritance" rule, until I start stepping in the world of Java GUI. In my experience, for adding custom requirements in a GUI components, for example, add ...
1
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1answer
45 views

Can composition be used in unit/integration testing over inheritance

In larger projects, there can often be a group of tests that test the functionality of related classes. These tests often share a lot of setup and preparation functionality. What happens then is ...
1
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1answer
136 views

Inheritance is better or composition design pattern in this scenario?

Design and implement Cash Register: Given a number of items you will be required to calculate the total bill. Items are charged for in a couple of different ways: A given price for each item, e.g. ...
0
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1answer
51 views

Should I always use prefix private methods with an underscore in Python?

Prefixing methods and members with an underscore indicates internal use. For simple classes, I sometimes find the easier reading and typing of self.foo outweighing the indent of self._foo. Especially ...
2
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0answers
56 views

Adding behaviour to a part of a third party class

I am working with an effectively third-party library. This library has a base class that's used as the interface (C++ style), ComponentBase. ComponentBase has a number of methods and setters that are ...
2
votes
1answer
106 views

Designing generic operations in object oriented languages

I found an interesting quote in SICP that I think is highly relevant in object oriented design: We see that, in general, a type may have more than one subtype. Triangles and quadrilaterals, for ...
0
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0answers
45 views

Code Duplication After Dependency Injection Instead Of Inheritance

I'm applying Dependency Injection instead of Inheritance. But now, I've the problem of code duplication. Main Controller final class PreferenceController implements PreferenceInterface { ...
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1answer
300 views

What is disinheritance in object oriented programming? [closed]

I am confused over Virtual Inheritance and disinheritance ? Is both are same ?
0
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0answers
25 views

Abilities interacting with aspects of other abilities - how to implement efficiently

In my game I want characters to be able to cast spells which deal a certain amount of damage of a certain type to other characters in the game. I also want abilities that negate an amount of damage ...
5
votes
1answer
124 views

Inheritance from children to parents?

Seeing this UML class diagram : FileHandler, Uploader and Deleter are abstract classes. The four bottom classes are implementations. They extend on FileHandlerInterface which requires a handle ...
17
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5answers
3k views

When to use inheritance, when to use 'just a boolean field'?

In our Rails application, we are adding notifications. Some of these are blocking: They stop the progress of whatever resource they are added on, because some information on that resource is missing. ...
3
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2answers
94 views

Creating Instances from same SuperClass Object

I have 3 subclasses (LowState, MediumState, HighState) which derive from the same superclass (State). Within the superclass, State, I have declared several variables which need to be accessed and ...
4
votes
2answers
113 views

Applying composition over inheritance to Vehicle classes

I have a car maintenance garage program that has an abstract Vehicle class that has several derived classes like Car MotorCycle, etc. Each of those derived vehicles in turn is either a fuel or an ...
2
votes
2answers
31 views

Refactor using CTI or create new Entities

I'm currently developing on a rather large e-commerce application that handles multiple different business-fields. Like every e-commerce application we have a Concept called an Order which has one or ...
35
votes
5answers
3k views

When should I extend a Java Swing class?

My current understanding of Inheritance implementation is that one should only extend a class if an IS-A relation is present. If the parent class can further have more specific child types with ...
8
votes
5answers
430 views

Inheritance vs additional property with null value

For classes with optional fields, is it better to use inheritance or a nullable property? Consider this example: class Book { private String name; } class BookWithColor extends Book { private ...
5
votes
3answers
217 views

Is it ever appropriate to use subtyping for a has-a relationship?

One of the basic precepts of object oriented programming is that subtyping represents the "is-a" relationship. That is, the child is always a specific form of the parent. A common example is that a ...
27
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3answers
5k views

If I implement an Interface, is it called an Inheritance?

If my class implements an interface then can I say that I'm following inheritance? I know that when a class extends another class then it's inheritance.
1
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1answer
85 views

Get or infer template type from inherited member

So I have an assignment from college where I have to apply multiple metaheuristics to different problems. I thought that I should make everything as modular and reusable as possible to reuse ...
3
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5answers
206 views

What is the correct OOP relation between complex and real numbers?

On one hand class complex { double real; double imaginary; } it is composition on the other hand class complex : double { double imaginary; } it is inheritance Which one is ...
-1
votes
2answers
109 views

Do you say “this” on protected members? [closed]

Background I have never had a formal class in OOP/OOD although I understand how the protected members work. Being accessible by any instance/derived class, they are thereby less private (more ...
3
votes
2answers
198 views

How do I deal with unneeded inherited members?

Consider the following UML diagram: In a nutshell: ChildClass1 and ChildClass2 use all of the members of ParentClass. ChildClass3only uses Member1 and Member2 and the value of Member5 is a ...
0
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2answers
98 views

Why is the _replace method of Python namedtuple classes protected?

In the section Method Names and Instance Variables, the Python Style Guide (aka PEP 0008) says, "Use one leading underscore only for non-public methods and instance variables." Why then, does the ...
1
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3answers
47 views

How to represent the following scenario in a class diagram?

Consider a store with multiple branches and a system generates reports for each branch monthly and annually and an overall report as well monthly and annually. So in total there are 4 types of ...
0
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1answer
75 views

How do you write super() in the UML format?Is it correct to write super(parameter: type): return type in the UML methods section?

Suppose you write a subclass that extends to a certain class and in that subclass, you use the super() method for your constructor. Would you write "super(parameter: type): return type" in the UML?
2
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3answers
108 views

Calling a constructor from a parent class in a derived class

I'm trying to create a parent class with a constructor that takes a single int as a parameter. I also need to derive a child class that creates two instances of the parent class using a constructor ...
3
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6answers
318 views

Can we say “If a parent class never appears in my codes except in its child class, it should be composition instead of inheritance”?

I read some posts about "composition over inheritance","where to use composition/inheritance" , "Is-a relationship..." or "Liskov substitution principle" for some time, but I am not sure if I get the ...
0
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2answers
199 views

Per my design requirements, does this design hierarchy seem reasonable?

Background Construction Note that I am using C# here, but it may not be necessary to provide input to my conceptual questions about design. Consider the following design methodology... I work at a ...
9
votes
3answers
318 views

Are Python mixins an anti-pattern?

I'm fully aware that pylint and other static analysis tools are not all-knowing, and sometimes their advice must be disobeyed. (This applies for various classes of messages, not just conventions.) ...
0
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3answers
202 views

What to do if I need more than one base class in C#? [closed]

Let's say I have a grid with square fields. For the fields I have an abstract Field class. This class has several subclasses, for example EmptyField or RoadField. Some of these fields can be connected ...
8
votes
7answers
395 views

A property that can represent both a single date and a date range: How to properly model that?

I work in a system that can represent a "shipping estimate" in two ways: A specific date: The item is guaranteed to ship at that date A day interval: The item will be shipped "X to Y" days from ...
1
vote
1answer
116 views

Is this a misuse of “composition over inheritance”?

The general sentiment seems to be that composition is preferable, in most cases, over inheritance, as it leads to less coupling. But for a case like this, module Publishable def new? @content....
2
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1answer
193 views

Creating multiple instances of an implementing class

I currently have an abstract class and multiple classes extending it. My problem is, that there has to be a way to create a variable number of instances of an extending class. The number of instances ...
2
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2answers
231 views

Child class accessing its parent's method from Ancestor method

I find myself right now banging my head with the following issue (in PHP): I have an abstract base class, which has a non-abstract method, inherited and unchanged all over the inheritance chain (...
5
votes
1answer
87 views

How do I more effectively design this per its intended design while ensuring I'm meeting SOLID design principles?

I know what SRP is, but am questioning my current design of an object I call an entity. Below is a picture of the design I am referring to. If I shift the code from the GeometricInformation and ...
1
vote
1answer
154 views

How to avoid having nested generic in class

I'm working on a side project, and I turned on all rules for code analysis in Visual Studio, and I got the warning notice: Warning CA1006 Consider a design where 'Vote<T>.CalculateWinner(...
3
votes
2answers
515 views

Cleanest way to expand a base class without explicitly mapping properties in C#

Lets assume I have following base class: public class Base { public int Id {get; set;} public string SomeText {get; set;} public string SomeOtherText {get; set;} public static Base ...
2
votes
2answers
230 views

Do common MVC frameworks violate the LSP and is there a MVC framework which does not?

You who have worked with a framework implementing the MVC architectural pattern most likely know how these frameworks are usually implemented. They contain a base Controller class, which you extend, ...
2
votes
0answers
224 views

Is it a good practice to use virtual inheritance as default? [closed]

Why virtual inheritance is not used as default? Default as in by the programmer and not the language. If not, why? What are the cases where it may fail? Is there some run time overhead? Is it ...
9
votes
4answers
505 views

Parallel hierarchies - partly same, partly different

There are quite a few similar questions out there 1, 2, 3, 4, but non seems exactly the case in this question, nor do the solutions seem optimal. This is a general OOP question, assuming polymorphism,...
6
votes
2answers
230 views

Is Python's inheritance an “is-a” style of inheritance or a compositional style?

Given that Python allows for multiple inheritance, what does idiomatic inheritance in Python look like? In languages with single inheritance, like Java, inheritance would be used when you could say ...
2
votes
2answers
200 views

What is meant by reuse of inheritance?

A 2013 study of 93 open source Java programs (of varying size) found that While there is [no] huge opportunity to replace inheritance with composition (...), the opportunity is significant (...
2
votes
2answers
250 views

How much implementation should I provide in an abstract class? [closed]

I have an abstract class AbstractService and about 10 classes that extend from AbstractService. However, I'm not sure how many methods and what methods I should implement in the abstract class and how ...
-1
votes
1answer
121 views

Inheritance hierarchy design approach - Javascript [closed]

For the below code, that creates inheritance hierarchy, function Animal(){ this.name = "Animal"; // toString is a function in the main Object that every // object inherits from this....
-4
votes
1answer
96 views

What actually happens in inheritance (java)? [closed]

class A { int a; int b; A(int i,int z) { a = i; } void abc() { System.out.println("a is " + a); System.out.println("b is " + b); } } class B ...
36
votes
5answers
2k views

How is defining that a method can be overridden a stronger commitment than defining that a method can be called?

From : http://www.artima.com/lejava/articles/designprinciples4.html Erich Gamma: I still think it's true even after ten years. Inheritance is a cool way to change behavior. But we know that it's ...
0
votes
2answers
118 views

Best practice for encapsulating a parameter that requires multiple interfaces to be implemented

I encounter this issue multiple times, but I'm never sure how best to deal with it. Basically, some methods I write require the implementing object to support multiple interfaces. The example I have ...
2
votes
3answers
97 views

Is there particular circumstance that throwing root superclass exceptions is a good practice?

I've been taught that exceptions should be have concise meanings and should contain a message that explains to the client what the exceptional situation is. I am wondering, since I found a piece of ...