Track 11 · Lesson 9 of 12

Composition

Build objects out of other objects, delegate work to the parts, and prefer has-a composition when inheritance doesn't fit.

You will be able to

• Recognise a has-a relationship and model it by storing objects as attributes
• Delegate work from an object to the objects it contains
• Build objects that hold and summarise lists of other objects
• Explain why composition is often a better choice than inheritance