Adding methods to Object in Rails -- WARNING

I wanted to do:


and wrap would go to a specialized wrap for some types of foo and a
general Object#wrap for all the others.

So I added wrap to Object

class Object
  def wrap

This worked except for objects which are actually AssociationProxy
objects pretending to be some other object. The reason is that
AssociationProxy removes all but a few methods from itself. You will
find this line at the top of

      instance_methods.each { |m| undef_method m unless m =~
/(^__|^nil\?$|^send$|proxy_)/ }

This happens before the files in initializers gets loaded. And that is
where I added Object#wrap. So, for a proxied object, it would call
Object#wrap instead of the specialized wrap that I had defined in my

My solution to this was to do this:

module ActiveRecord
  module Associations
    class AssociationProxy
      undef_method :wrap
      undef_method :unwrap

I *think* Rails could solve this problem by hooking into
Object.method_added. And when methods are added, the hook could undef
them for the proxy class(es). The other choice would be to subclass
AssociationProxy from BlankSlate rather than Object -- it appears that
that is what BlankSlate is intended to do.