Classes and dataclasses

Group data with the behaviour that belongs to it.

Beginner 15 min read Lesson 12 of 480 Challenge included

What you will be able to do

Define a class with methods
Generate boilerplate with @dataclass
Avoid shared mutable state

A class describes a kind of object: its data and the operations that make sense for that data. A dataclass writes the constructor and comparison methods for you.

classes.pyPython

from dataclasses import dataclass, field

@dataclass
class Learner:
    name: str
    scores: list[int] = field(default_factory=list)

    def average(self) -> float:
        return sum(self.scores) / len(self.scores) if self.scores else 0.0

    def passed(self, mark: float = 75) -> bool:
        return self.average() >= mark

ada = Learner("Ada", [88, 92, 79])
print(ada)
print(f"{ada.average():.1f}")
print(ada.passed())

Class: A template that describes objects.
Instance: One object created from a class.
Attribute: Data stored on an instance.
Method: A function defined on a class.
Dataclass: A decorator that generates common methods.

Your turn

Add a score method

Medium

Extend the Learner class with add_score() and print the updated average for a learner with two scores.

PYTHON · starter

from dataclasses import dataclass, field

@dataclass
class Learner:
    name: str
    scores: list[int] = field(default_factory=list)

    # add add_score() and average()

Check your understanding before moving on.

Knowledge checkQuestion 1

What does @dataclass generate by default?

Select an answer to continue

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Lesson 12 of 480 · 0% of course