From: Joel VanderWerf <vjoel@...>
Date: 2006-02-05T06:51:25+09:00
Subject: optional yield -- was Re: Quiz #65, Principle of Great Surprise, and Array.delete sledgehammer

Dave Howell wrote:
> And it had an optional "yield." I'm mystified as to how to make THAT
> part work, since neither ri nor the Pickaxe book gave me any hint at all
> as to how to detect IF a block is present, and yield if it is. Just
> using "yield" got me an error since I wasn't using a block in this case.

Use Kernel.block_given?, like this:

def one_two_three
  if block_given?; yield 1; yield 2; yield 3;
  else [1,2,3]
  end
end

See the PickAxe, in the chapter on blocks and iterators, page 51.

-- 
      vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407