From: Charles Oliver Nutter <charles.nutter@...>
Date: 2007-01-09T17:42:25+09:00
Subject: Re: [ ruby-Bugs-7680 ] a block argument within a block which argument has the same name leaks

Evan Phoenix wrote:
> Of course methods need local variables, but blocks would have local 
> variables still, just all in the scope of their defining method. Why do 
> closures need to have their own, unique variables outside of the scope 
> that they enclose? Smalltalk gets along quite well with all blocks 
> sharing the same local variable scope. The current scope rules are a 
> problem for a lot of new ruby programmers. Lots of them see the current 
> behavior as a bug that they have to work around.

Evan and I discussed this at length on IRC and I came up with one area 
that could be damaged by a "flat local scope": DSLs

In a large script using a complicated DSL, you would have to make sure 
all variables were named independently. Even worse, future revisions to 
that script would have to continue to maintain unique variable names 
across the entire script.

Evan and I do not see eye-to-eye on this, but we agree on many other points:

- no way to explicitly scope variables is confusing
- bugs arise from missing explicit scoping

And we disagree:

- I believe lexical scoping is useful and necessary even with problems
- I believe no lexical scoping would be far worse than not explicitly 
scoping variables

But we both speak from the point of view of Ruby implementers, so we do 
not know how correct or incorrect we may be.

-- 
Charles Oliver Nutter, JRuby Core Developer
Blogging on Ruby and Java @ headius.blogspot.com
Help spec out Ruby today! @ www.headius.com/rubyspec
headius@headius.com -- charles.nutter@sun.com