From: Josh Cheek <josh.cheek@...>
Date: 2010-12-31T02:04:58+09:00
Subject: Re: How to hook a callback through inheritance

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The problem is that before_laughing is being invoked as a class method on
Lol. So when you say "before_laughing :downcase_please", you aren't setting
@before_laughing on instances of Lol, but rather on Lol itself.

I suppose one way to do this is to leave the instance var on the class, then
just ask the class for its contents and execute them the same way. With this
implementation, that means you can't add callbacks for individual objects,
though.


class Lmao
  def initialize
    @str = "HAHAHAHAHAHHAHAHAH"
  end

  def self.inherited(base)
    base.extend Callbacks
  end

  def laughing
    self.class.before_laughing.each do |method|
      send method
    end
    @str
  end
end

module Callbacks
  def before_laughing(*methods)
    if methods.empty?
      @before_laughing ||= Array.new
    else
      @before_laughing = methods
    end
  end
end

class Lol < Lmao
  before_laughing :downcase_please

  def downcase_please
    @str.downcase!
  end
end

a = Lol.new
a.laughing # => "hahahahahahhahahah"

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