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Composition vs Inheritance

Composition vs Inheritance

In the previous session, we explored memoization and recursion, powerful techniques for optimizing code performance. Today, we embark on a new topic: Composition vs Inheritance. These two concepts are fundamental design patterns in object-oriented programming.

What is Composition?

Composition is a design pattern where objects are created by combining other objects. It's like building a car by assembling its individual components (engine, wheels, etc.).

Benefits of Composition

  • Flexibility: Allows for easy customization and adaptability.
  • Code Reusability: Components can be reused in multiple contexts.
  • Loose Coupling: Objects are loosely coupled, making it easier to modify and maintain.

Drawbacks of Composition

  • Increased Complexity: Can lead to more complex object structures.
  • Performance Overhead: Creating and managing many small objects can impact performance.
  • Not Suitable for Deep Hierarchies: Not ideal for situations where deep object inheritance is required.

When to Use Composition

  • When flexibility and customization are crucial.
  • When code reusability is a priority.
  • When loose coupling is desired.

What is Inheritance?

Inheritance is a design pattern where new objects (child classes) are created based on existing objects (parent classes). It's like creating a new type of car that inherits properties and behaviors from an existing car model.

Benefits of Inheritance

  • Code Reusability: Child classes inherit properties and methods from parent classes.
  • Reduced Code Duplication: Eliminates the need to rewrite common code in multiple classes.
  • Polymorphism: Child classes can override and extend methods inherited from parent classes, allowing for varied behavior.

Drawbacks of Inheritance

  • Rigid Structure: Can lead to inflexible and tightly coupled code.
  • Difficult to Modify: Changes in parent classes can impact child classes.
  • Not Suitable for Composition: Not ideal for scenarios where multiple inheritance or customization is required.

When to Use Inheritance

  • When code reusability and inheritance are essential.
  • When a clear parent-child relationship exists.
  • When polymorphism is desired.

Composition vs Inheritance: Key Differences

Object CreationAssembles existing objectsCreates new objects based on existing objects
Code ReusabilityHighHigh
CouplingLoosely coupledTightly coupled
PerformancePotentially slowerFaster

Example: Composition vs Inheritance with React Components

In React, we can use composition to create new components by combining existing components. For example, we can create a Button component that uses a Text component for the label and a View component for the container. This approach gives us flexibility and code reusability.

Best Practices for Composition

  • Favor composition over inheritance when possible.
  • Use interfaces to define contracts between objects.
  • Keep objects loosely coupled and avoid deep nesting.

Best Practices for Inheritance

  • Use inheritance when a clear parent-child relationship exists.
  • Avoid multiple inheritance and favor composition when possible.
  • Design classes with the open/closed principle in mind.

Code Example: Composition vs Inheritance

// Composition example const Button = (props) => { return {props.label}; }; // Inheritance example class Button extends React.Component { render() { return ; } }

Next Topic: Object Composition

In our next session, we'll dive deeper into Object Composition, exploring its benefits, techniques, and practical applications. Follow us for more JavaScript insights!