From: Joel VanderWerf <vjoel@...>
Date: 2004-06-02T05:23:30+09:00
Subject: Re: Blocks and Closures

Alex McHale wrote:
> If this is covered elsewhere, please point me in the right direction.
> 
> Either why, my question is what exactly is the difference between a
> block / closure of the syntax
> do |x, y|
>     ....
> end
> 
> versus
> 
> {|x, y|
>     ....
> }
> 
> Are these idioms identical in all but their syntax?  Or is there an
> underlying difference to them?
> 
> This has been bugging me for a while, and I haven't been able to
> locate the answer in the docs I've found.

The only difference is precedence:

def foo(*args, &bl)
   puts "foo got the block" if bl
end

def bar(*args, &bl)
   puts "bar got the block" if bl
end

foo bar {}      # ==> bar got the block
foo bar do end  # ==> foo got the block