From: "David A. Black" <dblack@...>
Date: 2004-08-21T22:31:04+09:00
Subject: Re: This naughty language of ours violates hallowed Structure Programming sophistries

Hi --

On Sat, 21 Aug 2004, Phlip wrote:

> Rubies:

(I think of myself more as a Ruby*ist*, but so be it :-)

> Ruby variables create into their method's scope, not their block's scope.
> That's why the above code works - it tweaks the Structured Programming
> rules. The element inside the if statement's blocks should, in theory, exit
> scope and disappear before the last element.

'if' doesn't create a new scope, but code blocks do:

$ ruby -e ' [1,2,3].each {|x| p x; y=1}; p x rescue puts $!; 
                                         p y rescue puts $!'
1
2
3
undefined local variable or method `x' for main:Object
undefined local variable or method `y' for main:Object

So the method/block scope distinction doesn't generally hold.  (This
is among the areas under revision for 2.0... so stay tuned.)  

The "in theory" bit is a little damning, since it suggests that Ruby's
design in this regard violates some general theory or principle, which
I don't think it does.  Having 'if' be of flat scope is a different
*practice* than other languages, but I don't think there's any
theoretical mandate to do it one way or the other.


David

-- 
David A. Black
dblack@wobblini.net