-- Homework 27, problem 1 -- solution.

local Point = {}
Point.__index = Point

function Point.new(x, y)
    local self = setmetatable({}, Point)
    self.x = x
    self.y = y
    return self
end

function Point:distance(other)
    local dx = self.x - other.x
    local dy = self.y - other.y
    return math.sqrt(dx * dx + dy * dy)
end

function Point:move(dx, dy)
    self.x = self.x + dx
    self.y = self.y + dy
end

local a = Point.new(0, 0)
local b = Point.new(3, 4)
print(a:distance(b))

a:move(1, 1)
print(a.x, a.y)
print(a:distance(b))