From: Bertram Scharpf <lists@...>
Date: 2007-02-08T22:06:58+09:00
Subject: Re: access to constants from instance_eval

Hi,

Am Donnerstag, 08. Feb 2007, 21:18:40 +0900 schrieb dblack@wobblini.net:
> On Thu, 8 Feb 2007, David Chelimsky wrote:
> 
> >irb(main):001:0> class Foo
> >irb(main):002:1>   BAR = "bar"
> >irb(main):003:1>   def bar
> >irb(main):004:2>     BAR
> >irb(main):005:2>   end
> >irb(main):006:1> end
> [...]
> >irb(main):011:0> foo.instance_eval { BAR }
> >NameError: uninitialized constant BAR
> 
> foo doesn't have any constants; only Foo does.  instance_eval changes
> self, but it's still in the same scope.  So the constants available
> inside the block are the same as those available outside the block.

`Scope' is not neccessarily "self":

  irb(main):001:0> class C ; X = "i" ; end
  => "i"
  irb(main):002:0> X = "o"
  => "o"
  irb(main):003:0> C.instance_eval { X }
  => "o"
  irb(main):004:0> C.class_eval { X }
  => "o"
  irb(main):005:0> C.instance_eval { self::X }
  => "i"
  irb(main):006:0> C.class_eval { self::X }
  => "i"
  irb(main):007:0>

Is there a documentation that explains the differences between "scope",
"context", "self" and whatelse?

Bertram


-- 
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de