implicit_to_s_and_to_str.rb

class Month_Sampler
  Months = { 'Jan' => "January", 'Feb' => "February", 'Mar' => "March", 'Apr' => "April", 
            'May' => "May", 'Jun' => "June", 'Jul' => "July", 'Aug' => "August", 
            'Sep' => "September", 'Oct' => "October", 'Nov' => "November", 'Dec' => "December"
  }

  # assign abbreviated and full month names depending on what is provided.
  # Because this is a sample short script, I simply fail if wrong input.
  def initialize month
    fail("Incorrect Month representation (as a string)") unless
    Months.has_value?(month) ? 
      (@full = month ; @abbr = Months.key @full ) :
      (@full = Months[month] ; @abbr = Months.key(@full))
  end
  # This is what we really want to look at...
  def to_s
    @abbr 
  end
  # to_str means more string like than to_s
  def to_str
    @full
  end

end

sample_month_1 = Month_Sampler.new "Jan"
sample_month_2 = Month_Sampler.new "October"
sample_month_3 = Month_Sampler.new "Sep"
puts "#{sample_month_1} shows with implicit to_s while << shows with implicit to_str like this: " << sample_month_1
puts "#{sample_month_2} shows with implicit to_s while the + uses implicit to_str like this: " + sample_month_2
puts "This format %s shows implicit to_s" % sample_month_3