Apprendre Ruby: semaine #3

# Anagram
def combine_anagrams(words)
  h = Hash.new
  words.each do |word|
    (h[word.downcase.chars.sort.join] ||= []) << word
  end
  h.values
end

words = ['Cars', 'for', 'potatoes', 'rAcs', 'four', 'scar', 'crEams', 'scream']
combine_anagrams(words)

########################################

# Custom attr_accessor with attribute value recording
class Class
  def attr_accessor_with_history(attr_name)
    attr_name = attr_name.id2name
    attr_reader attr_name
    attr_reader attr_name+"_history"
    class_eval %Q[
                  def #{attr_name}=(arg)
                    @#{attr_name} = arg
                    (@#{attr_name}_history ||= [nil]) << arg
                  end
      ]
  end
end

class Foo
    attr_accessor_with_history :bar
end

f = Foo.new
f.bar = 3
f.bar = :wowzo
f.bar = 'boo!'
f.bar_history # => [nil, 3, :wowzo, 'boo!']

########################################

# Palindrome?
def palindrome?(str)
  sanitized_string = str.gsub(/\W/, "").downcase
  sanitized_string == sanitized_string.reverse
end

palindrome?("A man, a plan, a canal -- Panama")


# Count ALL the words!
def count_words(str)
  sanitized_words = []
  word_occurences = {}
  
  str.gsub(/\w+/) {|word| sanitized_words << word.downcase}
  sanitized_words.each do |word|
    word_occurences[word] = (word_occurences[word] || 0) + 1
  end
  word_occurences
end

count_words("A man, a plan, a canal -- Panama")
count_words "Doo bee doo bee doo"