From: Rick DeNatale <rick.denatale@...>
Date: 2006-09-12T10:39:04+09:00
Subject: Re: Struggling with Blocks

On 9/11/06, Morton Goldberg <m_goldberg@ameritech.net> wrote:
> On Sep 11, 2006, at 1:55 PM, Rick DeNatale wrote:
>
> > So, what's the real deal with BEGIN..END.  What it really does is to
> > delimit a series of statements which are treated like an anonymous
> > method which is called in place.
>
> That's what I thought until recently, but there is a difference.
> Consider:
>
> <code>
> a = 1
> begin
>     a = 2
>     b = 3
>     p [a, b] # => [2, 3]
> end
> p a # => 2
> p b # => 3
> </code>
>
> If the begin ... end behaved _exactly_ like an anonymous method, we
> would see:
>
> <code>
> a = 1
> begin
>     a = 2
>     b = 3
>     p [a, b] # => [2, 3]
> end
> p a # => 1
> p b # => raises NameError
> </code>
>
> Frankly, I would be happier with the latter behavior.

I have to admit that I was struggling a bit when I made the analogy to
an anonymous method.  The key is that begin pushes a new stack frame
onto the call stack.

You are right about the scoping of local variables.
-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/