ruby-custom-compare-method.rb

# this example shows that in ruby you can
# define how an object is being compared
# to another object with a custom `==` method

class ProductItem
  attr_reader :name, :quantity

  def initialize(name, quantity)
    @name = name
    @quantity = quantity
  end

  def ==(other)
    puts "comparison made between #{self.name} and #{other.name}"
  end
end

p1 = ProductItem.new('coffee beans', 12)
p2 = ProductItem.new('aeropress', 5)

p1 == p2
p1.==(p2) # this is the verbose syntax
#=> comparison made between coffee beans and aeropress