From: Sean O'Halpin <sean.ohalpin@...>
Date: 2011-06-02T04:37:00+09:00
Subject: Re: instance variable in pseudo-global scope

On Wed, Jun 1, 2011 at 6:01 PM, Chad Perrin <code@apotheon.net> wrote:
> As I understand things:
>
> * Variables whose names have no leading sigil have local scope.
>
> * Instance variables are local scope for the particular instance of a
>  class within which they "live".
>
> * A Ruby program's "global" scope is actually the scope of an instance of
>  Object (or, under certain circumstances, maybe it could be an instance
>  of something further down the class inheritance hierarchy . . . ?).
>
> As such, it seems that within your program's "global" scope (not truly
> global, but close enough for government work in most cases), the
> effective difference between variables named foo and @foo is nothing but
> one character.  Is there some technical difference that might have an
> effect on the "behavior"[0] of the code I write, as long as neither of
> them is being exported to some other running code or enclosed in a more
> restricted scope within my program?
>
> ## NOTES
>
> [0]:  Someone actually flamed me for referring to the "behavior" of some
> code, once upon a time -- thus the scare quotes around behavior in this
> case.
>
> --
> Chad Perrin [ original content licensed OWL: http://owl.apotheon.org ]
>

Well, @vars in main are visible to methods defined in main. For example:

@foo = 1
foo = 1

def bar
  @foo = 10
end

def baz
  foo = 10
end

bar
baz

p @foo   # => 10
p foo    # => 2

Is that the kind of difference you're interested in?

Regards,
Sean