Inspired by @JEG2's talk at Rubyconf... Any ruby object, as a webapp! 'Cause we can. :-)

webapp.rb

require 'rubygems'
require 'rack'

class Object
  def webapp
    class << self
       define_method :call do |env|
         func, *attrs = env['PATH_INFO'].split('/').reject(&:empty?)
         [200, {}, send(func, *attrs)]
       end
    end
    self
  end
end

Rack::Handler::Mongrel.run [].webapp, :Port => 9292
#                         ^^^^^^^^^^^
#                              |          (x)
#                         ROFLSCALE DB ---/
#


# http://localhost:9292/push/1  -> 1
# http://localhost:9292/push/2  -> 12
# http://localhost:9292/push/3  -> 123

# http://localhost:9292/to_a    -> 123

# http://localhost:9292/pop     -> 3
# http://localhost:9292/shift   -> 1

# Implementations in other languages (thanks guys!):
# Node.js: https://gist.github.com/700995
# Groovy: https://gist.github.com/702337
# Python: https://gist.github.com/702001
# Perl w/ plack: https://gist.github.com/703620
# Perl w/ continuity: https://gist.github.com/703651
# Io: https://gist.github.com/703431

# Great explanation of how this works in Ruby on Stackoverflow:
# http://stackoverflow.com/questions/4198883/exposing-any-ruby-object-over-the-web

How come you didn’t settle with def self.call(env) instead?

require 'rack'

class Object
  def to_webapp
    def self.call(env)
      func, *attrs = env['PATH_INFO'].split('/').reject(&:empty?)
      [200, {}, send(func || :inspect, *attrs)]
    end
    self
  end
end

Rack::Handler::WEBrick.run [].to_webapp, :Port => 9292