Scala-like case class pattern matching in Python >= 3.10

match_case.py

import math
from dataclasses import dataclass
from math import sqrt

"""
    Scala-like case class pattern mathing in python >= 3.10
"""


@dataclass(frozen=True)
class Shape:
    """trait"""
    pass


@dataclass(frozen=True)
class Circle(Shape):
    """case class"""
    radius: int


@dataclass(frozen=True)
class Square(Shape):
    """case class"""
    side: int


@dataclass(frozen=True)
class Triangle(Shape):
    """case class"""
    a: int
    b: int
    c: int


def heron(a: int, b: int, c: int) -> float:
    s: float = (a + b + c) / 2
    return sqrt(s * (s - a) * (s - b) * (s - c))


def shape_area(s: Shape) -> float:
    match s:
        case Circle(radius):
            return math.pi * (radius ** 2)
        case Square(side):
            return side ** 2
        case Triangle(a, b, c):
            return heron(a, b, c)
        case _:
            raise f"Cannot handle shape {s.__class__.__name__}"


c = Circle(12)
s = Square(13)
t = Triangle(3, 4, 5)

print(f"Circle({c.radius}): {shape_area(c):.2f}")
print(f"Square({s.side}): {shape_area(s)}:2f")
print(f"Triangle({t.a, t.b, t.c}): {shape_area(t):.2f}")