Set Basics

Ruby's Set class stores unique values and makes membership checks direct.

set_basics.rb

require "set"

candidate = 
topics = Set.new(["ruby", "docs"])

added = topics.add?(candidate)
contains_candidate = topics.include?(candidate)
sorted_topics = topics.to_a.sort
topic_list = sorted_topics.join("/")

puts "candidate=#{candidate}"
puts "added=#{!added.nil?}"
puts "contains=#{contains_candidate}"
puts "topics=#{topic_list}"

require "set"

candidate = 
topics = Set.new(["ruby", "docs"])

added = topics.add?(candidate)
contains_candidate = topics.include?(candidate)
sorted_topics = topics.to_a.sort
topic_list = sorted_topics.join("/")

puts "candidate=#{candidate}"
puts "added=#{!added.nil?}"
puts "contains=#{contains_candidate}"
puts "topics=#{topic_list}"

require "set"

candidate = 
topics = Set.new(["ruby", "docs"])

added = topics.add?(candidate)
contains_candidate = topics.include?(candidate)
sorted_topics = topics.to_a.sort
topic_list = sorted_topics.join("/")

puts "candidate=#{candidate}"
puts "added=#{!added.nil?}"
puts "contains=#{contains_candidate}"
puts "topics=#{topic_list}"

set A `Set` keeps one copy of each value, so adding a duplicate does not increase the size.