From: dblack@...
Date: 2003-05-21T23:59:07+09:00
Subject: Re: module constant access

Hi --

On Wed, 21 May 2003, Dan Janowski wrote:

>
> On Wednesday, May 21, 2003, at 10:25 America/New_York, ts wrote:
>
> >>>>>> "D" == Dan Janowski <danj@3skel.com> writes:
> >
> > D> irb(main):013:0> module Trouble
> >
> >  When you write this, this is like if you write
> >
> >    Trouble = Module.new
> >
>
> Sure. This makes sense. But why the difference in visibility of the
> constant Trouble?

It's not exactly visibility -- const_defined? tells you whether that
constant was/is defined in that module, not just whether the module
can see it.  For example:

  irb(main):001:0> class A; X = 1; end
  => 1
  irb(main):002:0> class B < A; end
  => nil
  irb(main):003:0> B::X
  => 1
  irb(main):004:0> A.const_defined?("X")
  => true
  irb(main):005:0> B.const_defined?("X")
  => false
  irb(main):006:0> class B; X = 2; end
  => 2
  irb(main):007:0> B.const_defined?("X")
  => true


David

-- 
David Alan Black
home: dblack@superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav