Need to do something in an odd, non-standard ratio of time? Say 13 out of 17 times? Use PassFailinator to accomplish this feat!

pass_failinator.rb

# Simple class that lets you to define a custom ratio of when to let something
# occur veruses not.
#
# Inspiration: We've all done the 'index % 5 == 0' to act as a gatekeeper to
# some action, typically when creating test data. However, this works find when
# you want a standard occurance rate: half the time, third of the time, 25% of
# the time. I had a need to generate test data 40% (2 out 5) times. I'm not
# smart enough to calculate a mod that would work for me. So I created a brute-
# force method that included a variable, some checking, some incrementing, and
# voila: 40% of the time I was able to create data.
#
# PassFailiantor is the result of generalizing my solution to allow /any/
# ratio: 6 of 50, 7 of 9, 13 of 27, etc. Initialize an instance with the number
# of times you want it to allow within the total number of guesses. For example
#
# gatekeeper = PassFailinator.new(2,5)
# 5.times { puts gatekeeper.allow? }
# => will output two trues, followed by three falses
class PassFailinator

  def initialize(allows, guesses)
    @counter = 0
    @allows, @guesses = allows, guesses
  end

  def allow?
    result = can_allow?
    increment_counter
    reset_counter 
    return result
  end
  
  private
  
  def can_allow?
    @counter < @allows
  end
  
  def increment_counter
    @counter += 1
  end
  
  def reset_counter
    @counter = 0 if time_to_reset?
  end
  
  def time_to_reset?
    @counter == @guesses
  end

end