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Learn Core Principles of Composition | Section
Object-Oriented Programming in Python

bookCore Principles of Composition

Composition focuses on building complex objects by combining simpler, independent components. Instead of relying on inheritance, which creates rigid hierarchies, composition allows classes to collaborate through contained objects. This approach makes systems more flexible, modular, and easier to maintain, since components can be replaced or extended without breaking the entire structure.

example.py

example.py

copy

Order does not implement payment, inventory, or shipping logic itself. Instead, it has separate objects (Payment, Inventory, Shipping) and uses them to complete its work.

Each component has one responsibility, and Order only coordinates them. If you want to change how payment or shipping works, you can replace the component without modifying the Order class.

A few pitfalls to watch for when using composition are creating god objects that collect too many components and become difficult to manage, leaking component APIs through the outer class instead of keeping a clean interface, and introducing hidden coupling when components depend too much on each other's internal details.

God objects
expand arrow

A god object tries to do too much. It holds many components and handles many responsibilities, which makes the class hard to understand, test, and maintain.

Leaking component APIs
expand arrow

This happens when the outer class exposes the internal methods or attributes of its components. Instead of providing its own clean interface, it forces users to interact with internal objects directly.

Hidden coupling
expand arrow

Components become tightly connected through internal details. Changing one part unexpectedly breaks another because they rely on each other's internal structure instead of clear contracts.

question mark

What is a common risk when using composition that can make the design harder to maintain?

Select the correct answer

Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 1. ChapterΒ 16

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bookCore Principles of Composition

Swipe to show menu

Composition focuses on building complex objects by combining simpler, independent components. Instead of relying on inheritance, which creates rigid hierarchies, composition allows classes to collaborate through contained objects. This approach makes systems more flexible, modular, and easier to maintain, since components can be replaced or extended without breaking the entire structure.

example.py

example.py

copy

Order does not implement payment, inventory, or shipping logic itself. Instead, it has separate objects (Payment, Inventory, Shipping) and uses them to complete its work.

Each component has one responsibility, and Order only coordinates them. If you want to change how payment or shipping works, you can replace the component without modifying the Order class.

A few pitfalls to watch for when using composition are creating god objects that collect too many components and become difficult to manage, leaking component APIs through the outer class instead of keeping a clean interface, and introducing hidden coupling when components depend too much on each other's internal details.

God objects
expand arrow

A god object tries to do too much. It holds many components and handles many responsibilities, which makes the class hard to understand, test, and maintain.

Leaking component APIs
expand arrow

This happens when the outer class exposes the internal methods or attributes of its components. Instead of providing its own clean interface, it forces users to interact with internal objects directly.

Hidden coupling
expand arrow

Components become tightly connected through internal details. Changing one part unexpectedly breaks another because they rely on each other's internal structure instead of clear contracts.

question mark

What is a common risk when using composition that can make the design harder to maintain?

Select the correct answer

Everything was clear?

How can we improve it?

Thanks for your feedback!

SectionΒ 1. ChapterΒ 16
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