denisdefreyne

case 14
when 10..15
  puts "Kinda small!"
when 80..99
  puts "Kinda large!"
end

denisdefreyne

10..15 === 14   # => true
80..99 === 14   # => false

denisdefreyne

point.x = 10
p point.hash               # => 910895
p collection.key?(point)   # => false

denisdefreyne

point = Point.new(5, 6)

collection = {}
collection[point] = 42

p point.hash               # => 421522
p collection.key?(point)   # => true

denisdefreyne

require "set"

home = Path.new("home", "denis")
also_home = Path.new("home", "denis")
elsewhere = Path.new("usr", "bin")

paths = Set.new
paths << home

paths.include?(home)        # => true

denisdefreyne

require "set"

points = Set.new
points << Point.new(11, 24)

points.include?(Point.new(11, 24))   # => true
points.include?(Point.new(10, 22))   # => false

denisdefreyne

points = {}
points[Point.new(11, 24)] = true

points[Point.new(11, 24)]   # => true
points[Point.new(10, 22)]   # => nil

denisdefreyne

class Point
  # …
  def hash
    [self.class, @x, @y].hash
  end
end

denisdefreyne

class Point
  # …
  def hash
    # Do not do this!
    self.class.hash ^ (@x.hash * 3) ^ (@y.hash * 5)
  end
end

denisdefreyne

class Point
  # …
  def hash
    # Do not do this!
    self.class.hash ^ @x.hash ^ @y.hash
  end
end