From: Christopher Dicely <cmdicely@...>
Date: 2009-03-16T06:00:59+09:00
Subject: Re: Problem With eval and each_index

On Sun, Mar 15, 2009 at 10:27 AM, Jeff Schwab <jeff@schwabcenter.com> wrote:
> Christopher Dicely wrote:
>
>> Ruby blocks are closures
>
> That was not my understanding.  How does one return a block from a function?
>  (That's not a rhetorical question; I'm eager to learn.)

While block are closures, they aren't first-class. You can't return a
block, because its not a normal Ruby object. You can return an
instance of class Proc built from a particular block, though, and use
it outside the method in which it was created.

For example:

irb(main):001:0> def counter(seed=0)
irb(main):002:1> lambda { seed += 1 }
irb(main):003:1> end
=> nil
irb(main):004:0> c = counter(0)
=> #<Proc:0x02bcfaf0@(irb):2>
irb(main):005:0> c.call
=> 1
irb(main):006:0> c.call
=> 2