From: Robert Klemme <shortcutter@...>
Date: 2013-03-02T08:46:50+09:00
Subject: Re: Does `self` and `scope(local)` operate parallels?

On Fri, Mar 1, 2013 at 9:00 PM, Hans Mackowiak <lists@ruby-forum.com> wrote:
> self and the "local scope" are the same

Certainly not.  self is an object reference which cannot be changed by
the user. A scope is something that holds named object references
(local variables).  self can change
 - on method entry
 - when opening a class or module body
 - inside a block when executed via #instance_eval, #instance_exec,
#class_eval or #module_eval

Local scope changes
 - on method entry
 - inside blocks
 - inside class and module bodies

irb(main):001:0> def f(x=0)
irb(main):002:1> p self, local_variables.sort
irb(main):003:1> 1.times do |y|
irb(main):004:2* p self, local_variables.sort
irb(main):005:2> end
irb(main):006:1> p self, local_variables.sort
irb(main):007:1> end
=> nil
irb(main):008:0> f
main
[:x]
main
[:x, :y]
main
[:x]
=> [main, [:x]]

> and they only change when you do something like instance_eval

Correct.

> or other stuff like Threads

Wrong for self.

irb(main):015:0* p self
main
=> main
irb(main):016:0> Thread.new { p self }.join
main
=> #<Thread:0x802a8430 dead>

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/