OOP greetings example for Mirv in Ruby SO chat

greetings.rb

class TimeRange

  def initialize(start_hour, stop_hour)
    @start_hour = start_hour
    @stop_hour = stop_hour
  end
  
  def complete?
    @start_hour && @stop_hour
  end

  def include?(hour)
    return false unless complete?
    (@start_hour..@stop_hour).include?(hour)
  end

end

class Greeting
  
  def self.from_hash(h)
    message = h.fetch(:message)
    time_range = TimeRange.new(h.fetch(:start), h.fetch(:stop))
    new(message, time_range)
  end
  
  def initialize(message, time_range)
    @message = message
    @time_range = time_range
  end
  
  def in_effect?(hour)
    @time_range.include?(hour)
  end

end

class Greetings
  
  def self.from_array_of_hashes(a)
    a.map do |h|
      Greeting.from_hash(h)
    end
  end

  def initialize(greetings)
    @greetings = greetings + [default_greeting]
  end
  
  def find(hour)
    @greetings.find do |greeting|
      greeting.in_effect?(hour)
    end
  end
  
  private
  
  def default_greeting
    Greeting.new("Greetings!", TimeRange.new(0, 24))
  end

end