# Alias method in module **URL:** \ **Category:** ruby-talk\ **Created:** [28 January 2011 14:45 UTC](https://rubytalk.org/t/alias-method-in-module/61620 "2011-01-28T14:45:25Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Dagnan](https://avatars.discourse-cdn.com/v4/letter/d/49beb7/32.png) [@Dagnan](https://rubytalk.org/u/Dagnan)\ **Post date:** [28 January 2011 14:45 UTC](https://rubytalk.org/t/alias-method-in-module/61620/1 "2011-01-28T14:45:25Z")
Hi. I'm trying to alias a method in a module and then overwriting this method (still having access to the old method). I tried the following code that does not seem to work with Ruby 1.9.2. Do you have an idea why? Thanks. class A   def foo     puts 'bar'   end end module Foo   def self.included(base)     base.class\_eval do       alias\_method :old\_foo, :foo #unless method\_defined?(:old\_foo)     end   end   def foo     puts 'foobar'     #old\_foo   end end A.send :include, Foo a = A.new a.foo #=\> bar ---
**Author:** ![botp1](https://avatars.discourse-cdn.com/v4/letter/b/6de8d8/32.png) [@botp1](https://rubytalk.org/u/botp1)\ **Post date:** [29 January 2011 05:10 UTC](https://rubytalk.org/t/alias-method-in-module/61620/2 "2011-01-29T05:10:35Z")
try class A def foo    puts 'bar' end end module Foo def self.included(base)    base.class\_eval do      alias\_method :old\_foo, :foo #unless method\_defined?(:old\_foo)    end end def initialize(\*args)   self.extend Foo::Overrider end module Overrider    def foo      puts 'foobar'      #old\_foo    end end end A.send :include, Foo a = A.new a.foo #=\> foobar a.old\_foo #=\>bar not just sure if that is the best way for modifying a class instance methods. i'd rather just use require if possible ... best regards -botp > **···** > > On Fri, Jan 28, 2011 at 10:45 PM, Dagnan \ wrote: > > > I'm trying to alias a method in a module and then overwriting this method (still having access to the old method). ---
**Author:** ![Su\_Zhang1](https://avatars.discourse-cdn.com/v4/letter/s/3da27b/32.png) [@Su\_Zhang1](https://rubytalk.org/u/Su_Zhang1)\ **Post date:** [31 January 2011 17:59 UTC](https://rubytalk.org/t/alias-method-in-module/61620/3 "2011-01-31T17:59:40Z")
As of Ruby 1.9, when you include a module M in a class C, an anonymous class is created and becomes the immediate superclass of C and subclass of C's original superclass. All instance methods of M will be inherited by C in the same old way. So it is actually M#foo who gets overridden (by its subclass C#foo); C#foo never gets redefined. This is how Ruby currently resolves name conflicts raised during mixin. If you call `super' in C#foo, it will route to M#foo. class A   def foo     puts 'bar'     super   end end module Foo   def foo     puts 'foobar'   end end A.send :include, Foo a = A.new a.foo # =\> bar\nfoobar > **···** > > -- > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). ---
**Author:** ![Dagnan](https://avatars.discourse-cdn.com/v4/letter/d/49beb7/32.png) [@Dagnan](https://rubytalk.org/u/Dagnan)\ **Post date:** [1 February 2011 15:31 UTC](https://rubytalk.org/t/alias-method-in-module/61620/4 "2011-02-01T15:31:00Z")
Thank you all for your answers. Remix and Prepend have not been updated since a few months. candlerb and bot Peña solution are interesting. ---
**Author:** ![Brian\_Candler](https://avatars.discourse-cdn.com/v4/letter/b/5f9b8f/32.png) [@Brian\_Candler](https://rubytalk.org/u/Brian_Candler)\ **Post date:** [29 January 2011 10:03 UTC](https://rubytalk.org/t/alias-method-in-module/61620/5 "2011-01-29T10:03:47Z")
Looks like when you include module Foo, the definition of foo in the class still takes precedence over the one in the newly-included module. This seems to work though: class A   def foo     puts 'bar'   end end module Foo   def self.included(base)     base.class\_eval do       alias\_method :old\_foo, :foo       def foo         puts 'foobar'         old\_foo       end     end   end end A.send :include, Foo a = A.new a.foo > **···** > > -- > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). ---
**Author:** ![Brian\_Candler](https://avatars.discourse-cdn.com/v4/letter/b/5f9b8f/32.png) [@Brian\_Candler](https://rubytalk.org/u/Brian_Candler)\ **Post date:** [31 January 2011 18:06 UTC](https://rubytalk.org/t/alias-method-in-module/61620/6 "2011-01-31T18:06:12Z")
Su Zhang wrote in post #978699: > class A >   def foo >     puts 'bar' >     super >   end > end > > module Foo >   def foo >     puts 'foobar' >   end > end > > A.send :include, Foo > > a = A.new > a.foo # =\> bar\nfoobar It's the same in 1.8.7. I think the OP was looking for a way to achieve the opposite behaviour: to import a module which would override the method in the class. > **···** > > -- > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![Adam\_Prescott1](https://avatars.discourse-cdn.com/v4/letter/a/2acd7d/32.png) [@Adam\_Prescott1](https://rubytalk.org/u/Adam_Prescott1)\ **Post date:** [1 February 2011 13:21 UTC](https://rubytalk.org/t/alias-method-in-module/61620/7 "2011-02-01T13:21:09Z")
John Mair (banisterfiend) has written some code to manipulate ancestor chains, two of which are Remix and Prepend: Remix: [GitHub - banister/remix: Ruby modules re-mixed and remastered](https://github.com/banister/remix) Prepend: [GitHub - banister/prepend: prepends modules in front of a class; so method lookup starts with the module](https://github.com/banister/prepend) Prepend should do exactly what you're looking for. > **···** > > On Mon, Jan 31, 2011 at 6:06 PM, Brian Candler \ wrote: > > > I think the OP was looking for a way to achieve the opposite behaviour: > > to import a module which would override the method in the class.