info.rb

module TopLevel
  class Foo
    def to_s
      "<An instance of Foo>"
    end
    alias inspect to_s

    class << self
      def to_s
        "<Foo's metaclass>"
      end
      
      class << self
        def to_s
          "<Foo's metaclass>'s metaclass"
        end
      end
    end
  end

  class Foo
    puts "class Foo"
    puts "self: #{self}"
    puts "nesting: #{Module.nesting.inspect}"

    def context
      "Method definition context: #{self}'s metaclass"
    end

    puts context rescue puts "Method definition context: #{self}"
  end

  puts

  Foo.class_eval do
    puts "Foo.class_eval"
    puts "self: #{self}"
    puts "nesting: #{Module.nesting.inspect}"

    def context
      "Method definition context: #{self}'s metaclass"
    end

    puts context rescue puts "Method definition context: #{self}"
  end

  puts

  class << Foo
    puts "class << Foo"
    puts "self: #{self}"
    puts "nesting: #{Module.nesting.inspect}"

    def context
      "Method definition context: #{self}'s metaclass"
    end

    puts context rescue puts "Method definition context: #{self}"
  end

  puts

  Foo.instance_eval do
    puts "Foo.instance_eval"
    puts "self: #{self}"
    puts "nesting: #{Module.nesting.inspect}"

    def context
      "Method definition context: #{self}'s metaclass"
    end

    puts context rescue puts "Method definition context: #{self}"
  end

  puts

  class << Foo.new
    puts "class << Foo.new"
    puts "self: #{self}"
    puts "nesting: #{Module.nesting.inspect}"

    def context
      "Method definition context: #{self}'s metaclass"
    end

    puts context rescue puts "Method definition context: #{self}"
  end

  puts

  Foo.new.instance_eval do
    puts "Foo.new.instance_eval"
    puts "self: #{self}"
    puts "nesting: #{Module.nesting.inspect}"

    def context
      "Method definition context: #{self}'s metaclass"
    end

    puts context rescue puts "Method definition context: #{self}"
  end

end