Source: Source: Python Morsels

Notes

Exercise was an introduction to using decorator syntax to get and set the values of class properties, and to providing a string representation by implementing __repr__.

My solution

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from math import pi

class Circle:
    def __init__(self, radius=1):
        self.radius = radius
        
    def __repr__(self):
        return f'Circle({self.radius})'

    @property
    def radius(self):
        return self.__radius

    @property
    def diameter(self):
        return self.__diameter
    
    @property
    def area(self):
        return self.__area

    @radius.setter
    def radius(self, radius):
        if radius < 0:
            raise ValueError("Radius cannot be negative")
        self.__radius = radius
        self.__diameter = 2 * radius
        self.set_area(radius)

    @diameter.setter
    def diameter(self, diameter):
        self.__diameter = diameter
        self.__radius = diameter / 2
        self.set_area(self.__radius)
        
    def set_area(self, radius):
        self.__area = pi * (radius ** 2)

Provided solutions

Identical to mine.