Track 11 · Lesson 2 of 12

__init__ and attributes

How __init__ and self set up each new object, with default values, derived attributes and validation.

You will be able to

• Explain what self refers to and why every method receives it
• Write an __init__ method with required and default parameters
• Store cleaned or derived values as instance attributes
• Reject invalid arguments in __init__ by raising ValueError or TypeError
• Avoid sharing one mutable default value between objects