alias_method_chain and monkey patching

Question

I want to monkey patch a method created for alias_method_chain but the overwritten method is not called

# foo.rb
require 'active_support/core_ext'

class Foo
  def foo
    "original foo"
  end

  def foo_with_flag
    "foo with flag"
  end

  alias_method_chain :foo, :flag
end

# foo_ext.rb
class Foo
  def foo_with_flag
    "overridden foo with flag"
  end
end

foo = Foo.new
foo.foo # => "foo with flag"
foo.foo_with_flag # => "overridden foo with flag"

How can I make Foo#foo use the last implementation of Foo#foo_with_flag ?

Answer 1

The first alias_method_chain do the alias_method :foo, :foo_with_flag (a copy of the first definition), when you redefine foo_with_flag :foo is still alias'ed to the first definition. You have to do alias_method :foo, :foo_with_flag again after the second definition (not the "whole chain").