How do you determine when to use composition over inheritance?

1 Concept Clarity

When considering composition over inheritance, it's essential to understand the concepts clearly. Inheritance is like a family tree where a child class inherits attributes and methods from a parent class. This can be useful for creating a hierarchy of classes with shared behavior. However, it can also lead to rigid and fragile code structures. Composition involves creating objects with references to other objects that provide the necessary functionality. This approach promotes flexibility by allowing you to mix and match capabilities as needed without being locked into a particular inheritance chain.

2 Flexibility Focus

Flexibility is a key factor in deciding between composition and inheritance. If you need your system to be adaptable and open to future changes, composition often provides a more versatile foundation. It allows you to change the behavior of your system at runtime by combining different components in new ways. In contrast, inheritance can lead to a fixed structure that might be harder to modify as your system evolves. By focusing on how your design might need to adapt to unforeseen requirements, you can better assess which approach will serve your long-term strategy.

3 Reusability Rule

Reusability is another critical consideration. Composition can enhance reusability by allowing you to use the same component in different contexts without the need for a common ancestor. Inheritance might seem like a good way to reuse code, but it can also introduce unnecessary dependencies and limitations. For example, if you inherit from a class just to reuse some of its functionality, you're also forced to inherit everything else it includes, which might not be relevant or desirable for the new class.

5 Performance Perspective

Performance considerations can influence the choice between composition and inheritance, though they should not be the sole deciding factor. In some cases, inheritance can lead to more efficient code because it facilitates the reuse of base class methods without the overhead of additional object references. However, this performance difference is often negligible compared to the benefits of having a more flexible and maintainable system through composition. Therefore, unless performance is a critical concern for your application, it's generally better to prioritize design principles over slight performance gains.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?