Definition of Composition
Composition refers to the arrangement of elements in a work of art, literature, or music. In visual art, composition refers to the placement of elements such as line, shape, color, and texture within the frame of the piece. In literature, composition refers to the arrangement of words and sentences to create coherent and meaningful work. In music, composition refers to the arrangement of sounds and melodies to create a piece of music. The composition can also refer to the act of creating such a work.
Definition of Inheritance
Inheritance is a mechanism in object-oriented programming languages that allows a class to inherit properties and methods from a parent class. The class that inherits the properties and methods is called a subclass or derived class, while the class from which the properties and methods are inherited is called the superclass or base class. This allows for code reuse and a more organized and efficient way of building and maintaining software. The subclass can also add or override certain properties and methods inherited from the superclass, making it more specific to its own needs.
Composition vs Inheritance – Differences
Composition and inheritance are both ways to reuse code and organize class relationships in object-oriented programming, but they have some key differences.
- Composition allows an object to have a reference to another object and use its functionality, while inheritance allows a class to inherit properties and methods from a parent class.
- Inheritance creates an “is-a” relationship between the subclass and superclass, meaning the subclass is a type of superclass. The composition creates a “has-a” relationship, meaning the object has a reference to another object.
- Inheritance can lead to tight coupling between classes, where a change in the superclass can have a ripple effect on the subclasses that inherit from it. Composition decouples the classes and allows for more flexibility in changing one class without affecting the others.
- Inheritance can be limited by the language support for multiple inheritances, while Composition can be composed of any number of objects, and the objects can be changed at runtime.
- Composition is more flexible as it allows you to change the behavior of an object by replacing the composed objects, while Inheritance relies on the behavior of the parent class and can be more restrictive.
It’s worth noting that both Composition and Inheritance have their use cases, and both can be used together in a program. The choice between the two depends on the requirements of the project and the design goals.
Comparison Chart
Here is a comparison chart that highlights some of the main differences between composition and inheritance:
| Composition | Inheritance |
|---|---|
| An object has a reference to another object | A class inherits properties and methods from a parent class |
| Creates a “has-a” relationship | Creates an “is-a” relationship |
| Decouples classes | This can lead to tight coupling between classes |
| Allows for more flexibility in changing one class without affecting the others | Changes in the superclass can have a ripple effect on the subclasses |
| Can be composed of any number of objects, and the objects can be changed at runtime | Inheritance can be limited by the language support for multiple inheritances |
| Allows you to change the behavior of an object by replacing the composed objects | Relies on the behavior of the parent class and can be more restrictive |
It’s worth noting that both Composition and Inheritance have their use cases, and both can be used together in a program. The choice between the two depends on the requirements of the project and the design goals.
Similarities Between Composition vs Inheritance
Composition and inheritance are both ways to reuse code and organize class relationships in object-oriented programming, and they have some similarities:
- Both Composition and Inheritance are used to reuse existing code and functionality.
- Both allow for a more organized and efficient way of building and maintaining software.
- Both allow for code reuse, resulting in less duplicated code and making it easier to maintain.
- Both Composition and Inheritance can be used to model the relationships between different classes.
- Both Composition and Inheritance can be used to define the structure of an application.
- Both Composition and Inheritance are the fundamental concepts of object-oriented programming and are widely used in different programming languages.
It’s worth noting that both Composition and Inheritance have their use cases, and both can be used together in a program. The choice between the two depends on the requirements of the project and the design goals.
Frequently Asked Questions
- What is the main difference between composition and inheritance?
Composition allows an object to have a reference to another object and use its functionality, while inheritance allows a class to inherit properties and methods from a parent class. The composition creates a “has-a” relationship, while inheritance creates an “is-a” relationship. - When should I use composition over inheritance?
The composition can be a better choice when you want to change the behavior of an object at runtime by replacing the composed objects, while inheritance relies on the behavior of the parent class and can be more restrictive. The composition can also lead to less tight coupling between classes, making it more flexible. - Can I use both composition and inheritance in the same program?
Yes, both composition and inheritance can be used together in a program. The choice between the two depends on the requirements of the project and the design goals. - What are the benefits of using composition over inheritance?
Composition allows for more flexibility in changing one class without affecting the others, and it can be composed of any number of objects, which can be changed at runtime. It also allows you to change the behavior of an object by replacing the composed objects. - What are the benefits of using inheritance over composition?
Inheritance allows for code reuse, and it can create a clean and organized structure for the classes in your program. It also creates an “is-a” relationship between the subclass and superclass, making it clear the relationship between them.
Reference Books
Here are some reference books that provide more information on composition and inheritance in object-oriented programming:
- “Design Patterns: Elements of Reusable Object-Oriented Software” by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides: This book is considered a classic in the field of software engineering and it provides a comprehensive overview of design patterns, including those related to composition and inheritance.
- “Head First Design Patterns” by Eric Freeman, Elisabeth Freeman, Bert Bates, and Kathy Sierra: This book is a beginner-friendly guide to design patterns that use examples and exercises to make the concepts easy to understand. It covers both composition and inheritance.
- “Effective Java” by Joshua Bloch: This book provides a comprehensive guide to best practices in Java programming and covers a wide range of topics, including composition and inheritance.
- “Clean Code: A Handbook of Agile Software Craftsmanship” by Robert C. Martin: This book provides guidelines and best practices for writing maintainable and readable code, and covers topics such as composition over inheritance.
- “Designing Object-Oriented Software” by Rebecca Wirfs-Brock and Alan McKean: This book provides an in-depth guide to object-oriented design, including the use of composition and inheritance.
These are just a few examples of books that cover composition and inheritance in object-oriented programming. There are many more books and resources available that can provide more detailed information and examples.
