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92
votes
14answers
24k views

Where does this concept of “favor composition over inheritance” come from?

In the last few months, the mantra "favor composition over inheritance" seems to have sprung up out of nowhere and become almost some sort of meme within the programming community. And every time I ...
37
votes
4answers
21k views

Why should I prefer composition over inheritance?

I always read that composition is to be preferred over inheritance. A blog post on unlike minds, for example, advocates using composition over inheritance, but I can't see how polymorphism is ...
38
votes
9answers
6k views

Code Smell: Inheritance Abuse [duplicate]

It's been generally accepted in the OO community that one should "favor composition over inheritance". On the other hand, inheritance does provide both polymorphism and a straightforward, terse way of ...
3
votes
1answer
636 views

Composition vs. Inheritance [duplicate]

Here's what is given: public interface Request {} // there are 20 subclasses of Request public class CreateUserRequest implements Request { @NotEmpty public String userName; } // request ...
4
votes
2answers
1k views

OOP - Composition, Components and Composites Example?

I've been reading a bit about OOP in relation to Composition, Components and Composites. I believe I understand the fundamental principle (not sure). Can someone please provide a code example of a ...
9
votes
5answers
1k views

How do we know to favour composition over generalisation is always the right choice?

Whether an object physically exists or not, we can choose to model it in different ways. We could arbitarily use generalisation or composition in many cases. However, the GoF principle of "favour ...
3
votes
7answers
1k views

Inheritance using non-abstract base class

This post is based on the question http://stackoverflow.com/questions/49002/prefer-composition-over-inheritance/11758048#comment15634305_11758048. Some people said - check whether there is “is-a” ...
4
votes
2answers
520 views

How to use the Decorator pattern to add little functionality to big objects?

This question regards the usage of the Decorator pattern to add little functionality to objects of large classes. Following the classic Decorator pattern, please consider the following class ...
0
votes
2answers
286 views

Inheritance versus Composition in a business application

I have a training management and tracking system, with a high level structure as follows: We have a Role1, e.g. Manager, Shift-boss, miner, etc. and a Candidate, training for that Role. The role has ...