L5·Intermediate/Advanced

🏷️Typing & Dataclasses

Static type hints and boilerplate-free classes.

typingdataclasshints

§ 1Hints

def f(x: int) -> str: — not enforced at runtime. Tools like mypy/pyright check them.

§ 2Modern generics (3.9+)

list[int], dict[str, int]. Union: X | Y. Optional: X | None.

§ 3@dataclass

Auto-generates __init__, __repr__, __eq__ from field annotations.

Example

1from dataclasses import dataclass
2
3@dataclass
4class Point:
5    x: float
6    y: float
7    def dist(self) -> float:
8        return (self.x**2 + self.y**2) ** 0.5
9
10print(Point(3, 4))
11print(Point(3, 4).dist())

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Checkpoint quiz

Question 1 / 2

Are Python type hints enforced at runtime?

Comprehensions

Pathlib & File I/O