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Ruby Ruby Modules Ruby Core Modules Enumerable

Andrew Smith
Andrew Smith
14,330 Points
Posted by Andrew Smith
Andrew Smith
14,330 Points

Why does "each" need to be redefined when the Enumerable module is included?

class Game
  include Enumerable
  attr_accessor :players

  def each(&block)
    players.each(&block)
  end

  def initialize
    @players = []
  end

  ...

  def score
    score = 0
    players.each do |player|
      score += player.score
    end
    score
  end
end

In the method definition of each above, .each is being called. Since you can't define something by referring to itself, I'm guessing this is an override of the .each default definition (if not, somebody please tell me what the .each call is doing in its own definition). Why do we have to do this redefinition when the Enumerable module is included in a class? Why doesn't the default definition of .each pass in whatever calls it into a block?

1 Answer

Seth Kroger
Seth Kroger
56,413 Points
Seth Kroger
Seth Kroger
56,413 Points

From what I see here, Game is not itself an Enumerable but does have a list (of players) that is. So in this case, instead of each() working on a list of Games it's redirecting to working on the list of players.

Andrew Smith
Andrew Smith
14,330 Points
Andrew Smith
Andrew Smith
14,330 Points

Thanks for your reply. I vaguely understand that each is being redirected to work on the list of players instead of Games. What puzzles me in this method specifically:

def each(&block)
  players.each(&block)
end

is that the each method is being called within its own definition. How is this permissible? Is the each that is being called on the players array different than the each that is the name of the method being written here? Is the method written here being tacked on to or modifying a pre-existing each method in Ruby's collection of built-in methods?

Seth Kroger
Seth Kroger
56,413 Points
Seth Kroger
Seth Kroger
56,413 Points

Yes, they are different methods from different classes with the same name. The one defined here is for the class Game, while players is of class Array/List (not sure which one) which has it's own definition of each.