Scoped implicit conversion in Ruby, code is http://github.com/lsegal/ruby/tree/implicit

snippet.rb

class MyString < String
  def foo; reverse + "X" end
end

module Foo
  implicit String => MyString

  class A
    attr_reader :myattr
    def initialize
      @myattr = "hello"
    end
  end
end

p Foo::A.new.myattr.foo
p "hello".foo
# "ollehX"
# test.rb:17:in `<main>': undefined method `foo' for "hello":String (NoMethodError)

That took me a minute to parse. Pretty cool.

Great! Threads like this(http://news.ycombinator.com/item?id=1548670) show how much value this would add on Ruby's trunk. Hope it makes it there soon (on both 1.8.8 and 1.9.3)