L4·OOP & Errors

🎛️Properties & Descriptors

Computed attributes and the descriptor protocol.

propertydescriptorgettersetter

§ 1@property

Turn a method into a read-only attribute. Add @x.setter for writes and @x.deleter for delete.

§ 2Descriptors

A class implementing __get__/__set__/__delete__ is a descriptor. property is built on this.

Example

1class Circle:
2    def __init__(self, r): self.r = r
3    @property
4    def area(self):
5        return 3.14159 * self.r ** 2
6
7c = Circle(5)
8print(c.area)  # attribute access, but computed

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Question 1 / 2

Accessing c.area calls:

Dunder Methods

Exceptions