ticket_dispenser_machine_singleton.rb

# frozen_string_literal: true

# The singleton pattern is used when you need to ensure that only one instance of a class exists
# and provide a global point of access to it.
#
# The most common reason to use this design pattern is to control access to some shared resource,
# for example a database or a file.
# The second most common reason is to create a global variable whose change is more controlled.
class TicketDispenserMachine
  private_class_method :new

  def initialize
    @ticket_number = 0
  end

  def self.instance
    @instance ||= new
  end

  def take
    "Your ticket is ##{@ticket_number}".tap { @ticket_number += 1 }
  end
end

TicketDispenserMachine.instance.take

TicketDispenserMachine.new