Question regarding interaction between modules and classes

ruby-talk
1

Get uting @@foo instead of @foo

···

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----- Reply message -----
From: "Geometric Patterns" <geometric.patterns@gmail.com>
To: <ruby-talk@ruby-lang.org>
Subject: Question regarding interaction between modules and classes
Date: Sun, May 8, 2011 05:02

Hi,

In the code below, is there a way to learn @foo from $bar_one
using $bar_two?

Many thanks in advance!!

----------------

#!/usr/bin/ruby -w

module Foo
   def setup
      @foo = self.object_id
   end
   def foo
      return @foo
   end
end

class Bar
   include Foo
end

$bar_one = Bar.new
$bar_one.setup
p $bar_one.foo # => 2148224640

$bar_two = Bar.new
p $bar_two.foo # => warning: instance variable @foo not initialized

----------------

--
Posted via http://www.ruby-forum.com/.

2

Better: Don't use class variables. If there's a @@foo somewhere in the
ancestry tree of a module or class, this one will be used, instead of
what you set @@foo to in your own class.

A class method works much better:

class Klass
  @foo = "foo"
  def self.foo # note the self receiver. Very important!
    @foo
  end
end

Klass.foo
=> "foo"

To get @foo from another class:

class KlassTwo
  @foo = Klass.foo # Klass has to be defined before KlassTwo, obviously.
  def self.foo
    @foo
  end
end

···

On Sun, May 8, 2011 at 11:03 AM, uwe@kubosch.no <uwe@kubosch.no> wrote:

Get uting @@foo instead of @foo

--
Phillip Gawlowski

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(Ah, how soon!) they forget
When I've moved on to some other place,
There may be one or two,
When I've played and passed through,
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