From: "David A. Black" <dblack@...>
Date: 2004-04-15T01:03:51+09:00
Subject: Re: Interesting Scoping Rules

Hi --

On Thu, 15 Apr 2004, Charles Comstock wrote:

> I guess I should have qualified my statement a little better, I did 
> recognize that a def seems to be a hard scoping boundary, the question 
> was much more that I was very suprised by this, and was curious if 
> anyone had any insight as to WHY ruby chose to work things like this?

I think it's generally true that local variable scope changes every
time a new 'self' takes over:  

  class X
    # self is X
    def blah
      # self is any instance of X
    end
    # self is X again, back to where we were
  end

  class X
    # self is X but we've backed out of the class and
    # come back in, so we have a new local scope
  end

The design is flexible: you can use #define_method instead of def, if
you want to avoid changing self and therefore starting a new local
scope.  

> It suprises me much in the same way that we cannot def inside a def, it 
> will result in a new def at the top scope.  It also suprises me in the 
> way that if we stick a class inside of a class instance variables will 
> not bubble down into the inner class.

I'm not sure what you mean by that last one -- can you illustrate?


David

-- 
David A. Black
dblack@wobblini.net