Circle Class

Part of the Object Oriented Programming section of Coddy's Lua journey. Lesson 57 of 70.

Challenge

Easy

Let's continue building our Shape Manager by adding a Circle class alongside the Rectangle you created in the previous lesson.

You'll work with four files to keep your shapes organized:

Shape.lua: Your base Shape class with :new(name) and :getName().
Rectangle.lua: Your Rectangle class from the previous challenge with :getArea().
Circle.lua: Create a Circle class that inherits from Shape. The constructor should accept a radius, call the parent constructor with the name "Circle", and store the radius. Add a :getArea() method that calculates the circle's area using the formula πr². Use math.pi for the value of π.
main.lua: Require both your Rectangle and Circle modules. Read three values from input: a rectangle's width, a rectangle's height, and a circle's radius. Create one instance of each shape and print four lines: the rectangle's name, the rectangle's area, the circle's name, and the circle's area.

Both shapes now share the same interface through inheritance: each has a :getName() method from Shape and its own :getArea() implementation. This common interface will become useful in upcoming lessons.

Input: Three lines: width (number), height (number), and radius (number).

Output: Four lines: rectangle's name, rectangle's area, circle's name, circle's area.

Try it yourself

-- Require the Rectangle module
local Rectangle = require('Rectangle')

-- Require the Circle module
-- TODO: Require the Circle module here

-- Read width and height from input
local width = tonumber(io.read())
local height = tonumber(io.read())

-- TODO: Read the radius from input

-- Create a new Rectangle instance with the given dimensions
local rect = Rectangle:new(width, height)

-- TODO: Create a new Circle instance with the given radius

-- Print the rectangle's name and area
print(rect:getName())
print(rect:getArea())

-- TODO: Print the circle's name and area