Don't use each when you can use map

each_vs_map.rb

class Argument
	attr_reader :weight
	def initialize(weight)
		@weight = weight
	end
end

arguments = []
4.times { |i| arguments << Argument.new(i) }

#the long way to get all weights:
weights = []
arguments.each do |arg|
	weights << arg.weight
end
weights	#=> [0, 1, 2, 3]

#short way
weights = arguments.map(&:weight)
weights	#=> [0, 1, 2, 3]

#why don't get the sum of all weights?
sum = arguments.map(&:weight).inject{ |sum, n| sum + n }
sum #=> 6