OOPS - Composition vs. Inheritance

3 minute read

In the realm of programming, Object-Oriented Programming (OOP) stands tall as a paradigm that emphasizes the concept of objects. OOP allows developers to structure their code by modeling real-world entities as objects, each containing data and behaviors. One of the key principles of OOP is the ability to create relationships between objects, which is often achieved through inheritance and composition.

Understanding Inheritance in OOP

What is inheritance?

Inheritance is a mechanism in OOP that allows a new class to inherit properties and behaviors from an existing class, known as the superclass or parent class. The class that inherits these properties is called the subclass or child class.

How does inheritance work?

When a subclass inherits from a superclass, it gains access to all public and protected members of the superclass. This means that the subclass can reuse code from the superclass without having to re-implement it. Inheritance promotes code reusability and facilitates the creation of hierarchical relationships between classes.

Examples of inheritance

For example, consider a superclass Animal with properties and methods common to all animals. We can then create subclasses such as Dog and Cat, which inherit from the Animal class and add specific behaviors or characteristics unique to each subclass.

Explaining Composition in OOP

Definition of composition

Composition is another technique in OOP where objects are composed of other objects. Unlike inheritance, where the relationship between classes is hierarchical, composition involves creating objects that contain other objects as parts.

Differences between inheritance and composition

While inheritance promotes code reuse by allowing subclasses to inherit from superclasses, composition enables greater flexibility by allowing objects to be composed of other objects. In composition, the relationship between classes is typically less rigid compared to inheritance.

Advantages of composition over inheritance

One advantage of composition is that it promotes loosely coupled designs, making code more modular and easier to maintain. Additionally, composition allows for greater flexibility in changing the behavior of a class at runtime by swapping out components.

Examples illustrating Composition

Consider a class Car composed of various components such as Engine, Wheels, and Transmission. Each component can be independently modified or replaced without affecting the overall functionality of the Car class. This flexibility is a hallmark of composition.

Comparison between Composition and Inheritance

Pros and cons of both approaches

While inheritance simplifies code by promoting code reuse and establishing hierarchical relationships, it can lead to tight coupling between classes and introduce complexities in large codebases. Composition, on the other hand, fosters flexibility and modularity but may require more effort to implement initially.

When to use composition

Composition is often preferred when designing systems with interchangeable components or when there is a need for greater flexibility in modifying object behavior. It is particularly useful in scenarios where the relationship between classes is dynamic or non-hierarchical.

When to use inheritance

Inheritance is suitable for scenarios where classes exhibit a clear hierarchical relationship, and code reuse is a primary concern. It is commonly used when subclasses share a significant portion of functionality with their superclass and when promoting a standardized interface across related classes.


In conclusion, both composition and inheritance are powerful techniques in OOP, each with its own strengths and weaknesses. Understanding when to use composition versus inheritance is crucial for designing robust and maintainable software systems. By leveraging the strengths of both approaches judiciously, developers can create well-structured and flexible codebases.

Unique FAQs

  1. Q: Can composition and inheritance be used together? A: Yes, it’s possible to use both composition and inheritance in the same design. This approach, known as “composition over inheritance,” allows developers to combine the benefits of both techniques.

  2. Q: Is composition always preferable to inheritance? A: Not necessarily. The choice between composition and inheritance depends on the specific requirements of the design. In some cases, inheritance may offer a more natural and intuitive solution, while in others, composition may be more appropriate.

  3. Q: What are some common pitfalls to avoid when using inheritance? A: One common pitfall of inheritance is the risk of creating tightly coupled classes, where changes in the superclass can have unintended consequences on subclasses. Additionally, deep class hierarchies can lead to maintenance difficulties and code complexity.

  4. Q: How does composition promote code modularity? A: Composition allows objects to be constructed from smaller, more focused components, promoting a modular design. Each component can be developed and tested independently, making the codebase easier to understand and maintain.

  5. Q: Are there any performance considerations when choosing between composition and inheritance? A: While inheritance can lead to faster runtime performance due to static method dispatch, composition typically incurs a slight overhead in terms of object creation and method delegation. However, the difference in performance is often negligible and should not be a primary factor in the decision-making process.