From: Adam Prescott <mentionuse@...>
Date: 2011-02-03T08:39:50+09:00
Subject: Re: Amazing behavior of include module

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On Wed, Feb 2, 2011 at 11:15 PM, Andrew Wagner <wagner.andrew@gmail.com>wrote:

> This is really quite odd to me. Especially since AAA::BBB.constants returns
> an empty array. Anybody have an answer to this?
>
> On Wed, Feb 2, 2011 at 11:49 AM, Pavel Strnad <pavel.strnad@fel.cvut.cz
> >wrote:
>
> > Hi,
> > I do not understand how is following code working:
> > irb(main):001:0> module AAA
> > irb(main):002:1> class BBB
> > irb(main):003:2> end
> > irb(main):004:1> end
> > => nil
> > irb(main):005:0> BBB::BBB
> > NameError: uninitialized constant BBB
> >        from (irb):5
> >        from /usr/local/bin/irb:12:in `<main>'
> > irb(main):006:0> AAA::BBB::BBB
> > NameError: uninitialized constant AAA::BBB::BBB
> >        from (irb):6
> >        from /usr/local/bin/irb:12:in `<main>'
> > irb(main):007:0> include AAA
> > => Object
> > irb(main):008:0> BBB::BBB
> > => AAA::BBB
> > irb(main):009:0> BBB::BBB::BBB
> > => AAA::BBB
> > irb(main):010:0> BBB::BBB::BBB::BBB
> > => AAA::BBB
> > irb(main):011:0> AAA::BBB::BBB::BBB
>
> => AAA::BBB
> >
> > I thought that last four lines will not work, but they do. How is it
> > possible?
> > Thank you.
> > Pavel Strnad
> >
> >
>

Including AAA at the top level, as in line 7, acts the same as including it
on Object, so every object suddenly has BBB available to it.

module A; class B; end; end
include A
Object::A
Fixnum::A
class X; end
X::A
X.ancestors # => [X, Object, A, Kernel, BasicObject]

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