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Interloper adds before and after callback hooks to methods on POROs (plain old Ruby objects).


Add this line to your application's Gemfile:

gem 'interloper'

And then execute:

$ bundle

Or install it yourself as:

$ gem install interloper


To add before and after callbacks to a method:

require 'interloper'

class Foo
  include Interloper

  before(:do_something) { puts "do something before" }
  before(:do_something) { puts "do something else before" }
  after(:do_something) { puts "do something after" }
  after(:do_something) { puts "do something else after" }

  def do_something
    puts "doing it"


do something before
do something else before
doing it
do something after
do something else after
=> nil

Callbacks will receive the same arguments as the method being called.

require 'interloper'
class Foo
  include Interloper

  before(:do_something) do |x|
    puts "do something before, with #{x}"

  def do_something(something)
    puts "doing it with #{something}"
end"grace and style")


do something before, with grace and style
doing it with grace and style
 => nil 


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at Myers/interloper.