Proper capitalization for book titles

Question

I'm working through some exercises to sharpen my Ruby skills. The following code is how I solved this particular question. I'd like to know what other developers think of this solution. I'm self taught, which means: I'm not getting any feedback as I learn, so I just want to make sure that I'm learning the right way to do things. And I'd like to get a gauge of what professional developers think of my code.

Ranking System
[1-terrible] [2-not good] [3-ok] [4-good] [5-very good]

1. Is the answer code elegant? (score and feedback)
2. What tips can you suggest to improve the answer?
3. How's the readability of the code? (score and feedback)
4. Can you suggest a simpler and alternative answer?

Ruby

class Book
  def title
    @title
  end

  def title=(title)
  special_words = %w(and in the of a an)
  formatted_title = []

    @title = title.split.each_with_index do |w,i|
      case 
      when i == 0
        formatted_title << w.capitalize

      when i > 0 && !special_words.include?(w)
        formatted_title << w.capitalize

      when special_words.include?(w)
        formatted_title << w
      end
    end

  @title = formatted_title.join(" ")
  end
end

Rspec

describe Book do

  before do
    @book = Book.new
  end

  describe 'title' do
    it 'should capitalize the first letter' do
      @book.title = "inferno"
      @book.title.should == "Inferno"
    end

    it 'should capitalize every word' do
      @book.title = "stuart little"
      @book.title.should == "Stuart Little"
    end

    describe 'should capitalize every word except...' do
      describe 'articles' do
        specify 'the' do
          @book.title = "alexander the great"
          @book.title.should == "Alexander the Great"
        end

        specify 'a' do
          @book.title = "to kill a mockingbird"
          @book.title.should == "To Kill a Mockingbird"
        end

        specify 'an' do
          @book.title = "to eat an apple a day"
          @book.title.should == "To Eat an Apple a Day"
        end
      end

      specify 'conjunctions' do
        @book.title = "war and peace"
        @book.title.should == "War and Peace"
      end

      specify 'prepositions' do
        @book.title = "love in the time of cholera"
        @book.title.should == "Love in the Time of Cholera"
      end
    end

    describe 'should always capitalize...' do
      specify 'I' do
        @book.title = "what i wish i knew when i was 20"
        @book.title.should == "What I Wish I Knew When I Was 20"
      end

      specify 'the first word' do
        @book.title = "the man in the iron mask"
        @book.title.should == "The Man in the Iron Mask"
      end
    end
  end
end

Answer 1

Your code is readable, but it doesn't feel very "rubyish" to me. I think that's due to needing to setup and track some extra variables and track the index of the word in question -- having to case it depending on the index, etc.

It also bugs me a little bit that title= is doing so much. This is how I would have written it:

class Book
  def title
    @title
  end

  def title=(title)
    @title = titlieze(title)
  end

  private
  def titlieze(title)
    stop_words = %w(and in the of a an)
    title.capitalize.split.map{|w| stop_words.include?(w) ? w : w.capitalize}.join(' ')
  end

end

I used stop_words instead of special_words since that's a common naming scheme for search applications (ie. words you ignore when searching). I'd be tempted to move that into a constant or some other configuration, but it works fine for this.

Rspec output:

$ rspec -f d foo_spec.rb

Book
  title
    should capitalize the first letter
    should capitalize every word
    should capitalize every word except...
      conjunctions
      prepositions
      articles
        the
        a
        an
    should always capitalize...
      I
      the first word

Finished in 0.00261 seconds
9 examples, 0 failures

Answer 2

Your indentation is a bit inconsistent, making the code hard to read.

This short method

def title
  @title
end

… is commonly written using meta-programming.

The title= method could be improved by shortening it. There is too much reassignment going on: making an empty formatted_title, appending each word to it, then setting @title, but — just kidding! — we still have to re-join the words into a string! Better to do the job right the first time.

I also think that the code would be easier to understand by collapsing the three cases into two. Then you could easily state exactly when a word should be capitalized.

class Book
  attr_reader :title

  # Define this constant array just once
  @@SPECIAL_WORDS = %w(and in the of a an)

  def title=(title)
    @title = title.split.each_with_index.map do |w,i|
      case 
        when i == 0 || !@@SPECIAL_WORDS.include?(w)
          # Capitalize the first word and all subsequent non-special words
          w.capitalize
        else
          w
      end
    end.join(' ')
  end
end

Consider leaving words that already have internal capitalization unchanged (e.g. "iPhone").

Also consider that you might already have a String.titleize() if you're using ActiveSupport.

Answer 3

Though I am not a professional developer, I will venture one suggestion: learn how to use String methods and regexes to fullest advantage. Sometimes it is necessary to use split, partition, etc. to convert a string to an array of strings (possibly single-character strings), manipulate the array elements, then rejoin them into a string, but there is a lot you can do by working on the string directly. Here, for example, you can use String#gsub with a block:

str = "to eat an apple a day" 
sw = %w[and in the of a an]

str.capitalize.gsub( /\S+/ ) { |w| sw.include?(w) ? w : w.capitalize }
  #=> "To Eat an Apple a Day"

Edit: initially I had ...gsub( /\w+/ ).... I am grateful to @feed_me_code for the suggestion to use \S rather than \w.