Enumerator as an infinite generator in Ruby

Question

I\'m reading one resource explaining how Enumerators can be used as generators, which as an example like:

triangular_numbers = Enumerator.new do |yielder|
  numb         


        

Answer 1

The Yielder is just a piece of code that returns the value and wait until the next call.

This can be easily achieve by using the Ruby Fiber Class. See the following example that creates a SimpleEnumerator class:

class SimpleEnumerator

  def initialize &block
    # creates a new Fiber to be used as an Yielder
    @yielder  = Fiber.new do
      yield Fiber # call the block code. The same as: block.call Fiber
      raise StopIteration # raise an error if there is no more calls
    end
  end

  def next
    # return the value and wait until the next call
    @yielder.resume
  end

end

triangular_numbers = SimpleEnumerator.new do |yielder|
  number  = 0
  count   = 1
  loop do
    number  += count
    count   += 1
    yielder.yield number
  end
end

print triangular_numbers.next, " " 
print triangular_numbers.next, " " 
print triangular_numbers.next, " " 

I just replaced Enumerator.new in your code by SimpleEnumerator.new and the results are the same.

There is a "light weight cooperative concurrency"; using the Ruby documentation words, where the programmer schedules what should be done, in other words, the programmer can pause and resume the code block.