seconds_old.rb

require 'date'

# puts "What are you? #{ARGV} #{ARGV.class}"

# Called as in `ruby example2.rb 1977 10 30`
# birthdate = ARGV.map {|arg| arg.to_i }
birthdate = [ 1977, 10, 30 ]
# year, month, day = [ 1977, 10, 30 ]

# birth_in_seconds = Date.new(year,month,day).to_time.to_i
birth_in_seconds = Date.new(*birthdate).to_time.to_i
today_in_seconds = Date.today.to_time.to_i

age = today_in_seconds - birth_in_seconds

class Date
  EARTH_YEAR_IN_SECONDS = 31557600
end

def planet_years(age_in_seconds,ratio_to_earth_years)
  age_in_seconds / (Date::EARTH_YEAR_IN_SECONDS * ratio_to_earth_years)
end

def earth_years(age_in_seconds)
  planet_years(age_in_seconds,1)
end

def mercury_years(age_in_seconds)
  planet_years(age_in_seconds,0.2408467)
end

# ...

def neptune_years(age_in_seconds)
  planet_years(age_in_seconds,164.79132)
end

puts earth_years(age)
puts mercury_years(age)
puts neptune_years(age)