Methods

Classes & Objects, lesson 2 of 6

🏗️ Classes & Objects, lesson 2 of 6

Give objects behavior with functions that live inside the class.

10 min

1 exercise

1 quiz

0/2 solved

Getting Python ready… examples can run in a moment.

A method is a function defined inside a class. Its first parameter is always self, so it can read and change the object's attributes.

You call it with a dot: c.click(). Python passes c in as self automatically.

Example

Give click a parameter step=1 and use self.count += step, then call c.click(5).

Example

Methods can call other methods through self. After changing width, area() gives a new answer because it's computed on every call.

Quiz

What does this print?

2 ['a', 'b']

1 ['b']

2 ['b']

None ['a', 'b']

Objects can interact. A method can take another object as an argument and call its methods or change its attributes.

Example

Change the troll's power to 12. Who wins now?

Exercise

Complete the three methods of Cart:

add(name, price) appends a (name, price) tuple to self.items
total() returns the sum of all prices
most_expensive() returns the name of the priciest item, or None for an empty cart