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Versions: 131
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Contents
module BookKeeping
VERSION = 1
end
class Allergies
ALLERGENS = %w(eggs peanuts shellfish strawberries tomatoes chocolate pollen cats)
def initialize(score)
@score = score
end
def list
ALLERGENS.select do |item|
allergic_to?(item)
end
end
# This project uses a concept called bitflagging where each new allergen
# is a power of 2. If you want to see how this works, try using to_s(2)
# to turn @score into a binary string. `@score.to_s(2) #=> 100010` when
# @score == 34. The first 1 is chocolate, the second 1 is peanuts. 32 + 2
# == 34.
# This works because even if all the allergens below 'cats' were active,
# their total value would be 127.
def allergic_to?(item)
index = ALLERGENS.index(item)
# Use a Binary AND to see if this allergen's bit is active or not.
@score & (2**index) > 0
end
end
Version data entries
131 entries across 131 versions & 1 rubygems