Ruby

In second sample we don't have any warnings or errors with wrong comma after last attr_accessor attribute and without it is very difficult to identify the typo. initialize method does not performed.

It works¶

class Solution
  attr_accessor :one, :two, :three

  def initialize
    @one = @two = @three = []
    puts "Done!"
  end
end

solution = Solution.new
p solution.one
p solution.two
p solution.three

Result:¶

MacBook-Air-Roman% ruby ruby_solution.rb
Done!
[]
[]
[]

it does not work¶

class Solution
  attr_accessor :one, :two, :three,

  def initialize
    @one = @two = @three = []
    puts "Done!"
  end
end

solution = Solution.new
p solution.one
p solution.two
p solution.three

Result¶

MacBook-Air-Roman% ruby ruby_solution.rb
nil
nil
nil