From: Just Another Victim of the Ambient Morality <ihatespam@...>
Date: 2006-07-20T17:15:32+09:00
Subject: What's the difference between these two block passing strategies?

    A common complaint I hear about Ruby is (I think, I may quoting 
incorrectly or the wrong thing) that "blocks aren't first order object."  I 
won't pretend to know what that means but, in context, it appears that they 
are complaining about how you can't pass blocks around like variables.  In 
particular, I recall someone having to deal with some kind of UI toolkit 
that requied blocks but couldn't pass the blocks up the call stack.
    I was just fiddling around with Ruby and I think I have two ways to do 
this and I was wondering if there were any subtle differences between them 
or any gatchas that I might be missing.
    Please take a look at them.  Here's the first:


def foo
    yield
end

def bar(&lambda)
    foo &lambda
end

bar { puts "Blocks!" }


    ...and here's the second:


def foo
    yield
end

def bar
    foo { yield }
end

bar { puts "Blocks!" }


    ...so, what do you guys think?  Are they equivalent?  Is there a 
performance difference?  Are they even doing what I think they're doing?
    Thank you...