From: Rick DeNatale <rick.denatale@...>
Date: 2008-05-15T09:55:34+09:00
Subject: Re: Override methods from a module

On Mon, Oct 15, 2007 at 7:52 PM, Drew Olson <olsonas@gmail.com> wrote:
> Drew Olson wrote:
>> Your examples definitely help and may have helped me with another way of
>> looking at the problem but I'm not sure they'll work as my objects are
>> already extending parent objects.
>>
>> - Drew
>
> Sorry about the previous response. Apparently lack of sleep results in
> horrendous grammar. Below is the solution I've figured out for the
> problem. It seems to work the way I was hoping for. Please let me know
> if this makes sense/how this could be improved.
>
> Thanks,
> Drew
>
> module Stuff
>  def self.included mod
>    @@mixer_class = mod
>  end
>
>  def initialize
>    super
>    @@mixer_class.class_eval do
>      alias_method :old_setup, :setup
>      alias_method :old_teardown, :teardown
>
>      define_method(:setup) do
>        old_setup
>        puts "new setup"
>      end
>
>      define_method(:teardown) do
>        old_teardown
>        puts "new teardown"
>      end
>    end
>  end
> end
>
> class Tester
>  def common
>    puts "this is in all tests!"
>  end
> end
>
>
> class PlainTester < Tester
>  def setup
>    puts "plain setup"
>  end
>
>  def teardown
>    puts "plain teardown"
>  end
> end
>
> class ExtraFunTester < Tester
>  include Stuff
>  def setup
>    puts "old setup"
>  end
>
>  def teardown
>    puts "old teardown"
>  end
> end

Not a general solution:

module Stuff
 def self.included mod
   @@mixer_class = mod
 end

 def initialize
   super
   @@mixer_class.class_eval do
     alias_method :old_setup, :setup
     alias_method :old_teardown, :teardown

     define_method(:setup) do
       old_setup
       puts "new setup"
     end

     define_method(:teardown) do
       old_teardown
       puts "new teardown"
     end
   end
 end
end

class Tester
 def common
   puts "this is in all tests!"
 end
end


class PlainTester < Tester
 def setup
   puts "plain setup"
 end

 def teardown
   puts "plain teardown"
 end
end

class ExtraFunTester < Tester
 include Stuff
 def setup
   puts "old setup"
 end

 def teardown
   puts "old teardown"
 end
end

class FunkedUpTester < Tester
 include Stuff
 def setup
   puts "old setup"
 end

 def teardown
   puts "old teardown"
 end
end


p = PlainTester.new
e = ExtraFunTester.new
f = FunkedUpTester.new

puts "p.setup"
p.setup
p.teardown

puts "e.setup"
e.setup
e.teardown

puts "f.setup"
f.setup
f.teardown

RubyMate r8136 running Ruby r1.8.6
(/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby)
>>> untitled

p.setup
plain setup
plain teardown
e.setup
old setup
old teardown
f.setup
SystemStackError: stack level too deep

method setup	in untitled document at line 13
method old_setup	in untitled document at line 13
method setup	in untitled document at line 13
method old_setup	in untitled document at line 13
method setup	in untitled document at line 13
method old_setup	in untitled document at line 13
method setup	in untitled document at line 13
,
.
.
method old_setup	in untitled document at line 13
method setup	in untitled document at line 13
at top level	in untitled document at line 78



-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/