Attributes

Learn class and instance attributes.

Class attribute

A class attribute is a variable defined directly in the class body. All instances share this value.

Example: class Product:\n tax_rate = 0.18. Here tax_rate is a class attribute. It is accessed as Product.tax_rate or through an instance as p.tax_rate. The default value of a class attribute must be a constant.

Instance attribute

An instance attribute is data specific to each instance. It is assigned through self, usually inside the __init__ method. For now we can also assign it from outside.

Example: p = Product(); p.name = "Pen". Here p.name belongs only to p; another instance does not share the name value. An instance attribute is separate from a class attribute.

Exercise Add an attribute to the Product class

Define a class named Product. Add the class attribute tax_rate = 0.18 in the body. After the class, write print(Product.tax_rate).

Show example solution

# Define the Product class
class Product:
    tax_rate = 0.18

print(Product.tax_rate)

Test yourself

Complete the class attribute

class Product:
    ____ = 0.18

Show answer

class Product:
    tax_rate = 0.18

Which one is an instance attribute?
- class Product: tax_rate = 0.18
- p = Product(); p.name = "Pen"
- Product.tax_rate = 0.20
- class Product: pass
Show answer

p = Product(); p.name = "Pen" — The p.name assignment creates an instance attribute; it belongs only to p.
Match the attribute types

tax_rate = 0.18

Class attribute
self.name

Instance attribute
Product.tax_rate

Access via class

Next lesson: Methods

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