From: Yukihiro Matsumoto <matz@...>
Date: 2008-09-30T13:13:59+09:00
Subject: Re: ruby1.9 block scope

Hi,

In message "Re: ruby1.9 block scope"
    on Tue, 30 Sep 2008 09:10:39 +0900, Daniel DeLorme <dan-ml@dan42.com> writes:

|That was also my guess; it least it's an easy concept to imagine. But it 
|does bring the question of what to do when you *don't* want variables to 
|"escape" into the enclosing scope? e.g.
|
|class Foo
|   defined_method :bar do
|     x = 1  #I don't want x to be defined in the Foo scope
|   end
|   defined_method :baz do
|     x = 2  #because it would wind up shared with this method
|   end
|end

As Nobu stated, you can explicitly declare block local variables,
using ';'.  Besides that above code would not share variable x, since
the variable is not used upper level.   They are two distinct
variables at the same level, with a same name.  See the following
code, that makes a variables shared among blocks:

class Foo
   defined_method :bar do
     x = 1
   end
   defined_method :baz do
     x = 2
   end
   x = 45  # this assignment would make x shared with foo and bar under the new rule.
end

The reason I haven't introduced it yet in Ruby is that single
assignment after the blocks can change the scope of a variable
afterward.  Same thing happens assignments _before_ the blocks
already.  But I hesitated to enhance that far.

							matz.