Ruby equivalent of C#'s 'yield' keyword, or, creating sequences without preallocating memory

Question

In C#, you could do something like this:

public IEnumerable GetItems()
{
    for (int i=0; i<10000000; i++) {
        yield return i;
           


        

Answer 1

It's supported by Enumerator since Ruby 1.9 (and back-ported to 1.8.7). See Generator: Ruby.

Cliche example:

fib = Enumerator.new do |y|
  y.yield i = 0
  y.yield j = 1
  while true
    k = i + j
    y.yield k
    i = j
    j = k
  end
end

100.times { puts fib.next() }