When is the Enumerator::Yielder#yield method useful?

Question

The question \"Meaning of the word yield\" mentions the Enumerator::Yielder#yield method. I haven\'t used it before, and wonder under what circumstances it would be

Answer 1

Since Mladen mentioned getting other answers, I thought I would give an example of something I just did earlier today while writing an application that will receive data from multiple physical devices, analyze the data, and connect related data (that we see from multiple devices). This is a long-running application, and if I never threw away data (say, at least a day old with no updates), then it would grow infinitely large.

In the past, I would have done something like this:

delete_old_stuff if rand(300) == 0

and accomplish this using random numbers. However, this is not purely deterministic. I know that it will run approximately once every 300 evaluations (i.e. seconds), but it won't be exactly once every 300 times.

What I wrote up earlier looks like this:

counter = Enumerator.new do |y|
  a = (0..300)
  loop do
    a.each do |b|
      y.yield b
    end
    delete_old_stuff
  end
end

and I can replace delete_old_stuff if rand(300) == 0 with counter.next

Now, I'm sure there is a more efficient or pre-made way of doing this, but being sparked to play with Enumerator::Yielder#yield by your question and the linked question, this is what I came up with.