a.rb

module A
  refine(A) {}
  using A
end
#a.rb:3: stack level too deep (SystemStackError)

activerecord_with_refinements.rb

def require x
  if x.include? 'core_ext' and !x.include? 'psych'
    puts "wtf #{x}", caller.first
  else
    super
  end
end

module ActiveSupportCoreRefinements
  active_support_no_deps, active_support_deps =  Dir[Gem.find_files('active_support/core_ext').first.sub('.rb','') + "/**/*.rb"].partition do |core_ext|
    file_contents = open(core_ext).read
    !file_contents.match /require.*core_ext.*/
  end
  
  def self.refineify file_contents, file
    file_contents.gsub!(/^\s*require\s*.*core_ext.*\s*$/, '')
    if file_contents.gsub!(/^\s*(class|module) (\S*)\s*$/i, "refine \\2 do")
      eval file_contents rescue puts "#{file} failed to eval"
      puts 1.day, file  rescue print '.'
    end
  end

  ActiveSupportCoreRefinementsBase = Module.new  do
    active_support_no_deps.each do |core_ext|
      file_contents = open(core_ext).read
      ActiveSupportCoreRefinements.refineify file_contents, core_ext
    end
  end
  
  using ActiveSupportCoreRefinementsBase
  puts nil, "dependent"
  active_support_deps.each do |core_ext|
    file_contents = open(core_ext).read
    refineify file_contents, core_ext
  end
end

calling_methods_in_same_refinement.rb

module A
  refine String do
    def a
      puts "a"
    end
    def b
      a
    end
  end
end

using A
"b".b
# a

hide_refinement_in_other_refinement.rb

module A
  refine String do
    def a
      puts "a"
    end
  end
end


module B
  refine String do
    using A
    def b
      a
    end
  end
end

using A
using B
"b".b
#a

purely_lexically_scoped.rb

module A
  refine String do
    def a
      puts "a"
    end
  end
end


module B
  refine String do
    def b
      a
    end
  end
end

using A
using B
"b".b
#a.rb:13:in `b': undefined local variable or method `a' for "b":String (NameError)
#	from a.rb:20:in `<main>'

purely_lexically_scoped_two.rb

module A
  refine String do
    def a
      puts "a"
    end
  end
end


module B
  using A
  refine String do
    def b
      a
    end
  end
end

using A
using B
"b".b
# a

refinements_in_refinements_2.rb

module A
  refine Array do
    def b_me
      puts "b"
    end
  end
  refine String do
    using A
    def b
      [].b_me
    end
  end
end

using A
"b".b
# b

refinements_in_refinements_one.rb

module A
  refine String do
    using A
    def b
      [].b_me
    end
  end

  refine Array do
    def b_me
      puts "b"
    end
  end
end

using A
"b".b
#a.rb:5:in `b': undefined method `b_me' for []:Array (NoMethodError)
#	from a.rb:17:in `<main>'

refinements_in_separate_blocks_one.rb

module A
  refine String do
    def a
      puts "a"
    end
  end
  refine String do
    def b
      a
    end
  end
end

using A
"b".b
# a

refinements_in_separate_blocks_two.rb

module A
  refine String do
    def b
      a
    end
  end
  refine String do
    def a
      puts "a"
    end
  end
end

using A
"b".b
# a