Book Capitalization Class Error - ruby

Question

I'm teaching myself how to code and can't seem to understand how the inputted title is being called by this class. Where does the argument go to first? The attr_accessor or the def title capital_it(#title) end?
class Book
attr_accessor :title
def title
capital_it(#title)
end
def capital_it(title)
word_arr = #title.capitalize.split(" ")
word_arr.map do |word|
word.capitalize! unless little_words.include?(word)
end
word_arr.join(" ")
end
def little_words
["the", "a", "an", "and", "in", "of"]
end
end

Answer 1

Where does the argument go to first? The attr_accessor or the def title ... ?
attr_accessor :title defines two methods for you: title (the "reader") and title= (the "writer"). When you do def title after attr_accessor, you replace the title method entirely with your new method.
In other words, the method generated by attr_accessor is never called, because you've overwritten it with your own method.
Since you're writing your own "reader" method, you should just use attr_writer:
class Book
attr_writer :title
def title
capital_it(#title)
end
# ...
end

Answer 2

First of all, you have an issue in your def capital_it(title) method.
.map method will return a new array which you didn't assign to anything. If you want to reassign it to local variable word_arr use .map! instead.
You should probably rewrite condition word.capitalize! unless little_words.include?(word) to this little_words.include?(word) ? word : word.capitalize
P.S. In your case it works because you use capitalize! on each string of element but the style of writing like that isn't good.
So I'd recommend you to write your class like this one:
class Book
SKIP = %w(the a an and in of)
attr_writer :title
def initialize(title)
#title = title
end
def title
capital(#title)
end
private
def capital(title)
array = #title.split(/\s+/)
array.map! do |word|
SKIP.include?(word) ? word: word.capitalize
end
array.join(" ")
end
end