```ruby
require 'naught/null_class_builder/command'

module Naught::NullClassBuilder::Commands
  class Traceable < Naught::NullClassBuilder::Command
    def call
      defer do |subject|
        subject.module_eval do
          attr_reader :__file__, :__line__

          def initialize(options={})
            backtrace = options.fetch(:caller) { Kernel.caller(3) }
            @__file__, line, _ = backtrace[0].split(':')
            @__line__ = line.to_i
          end
        end
      end
    end
  end
end
```

Fix specs on Ruby 1.9
user
```ruby
require 'naught/null_class_builder/command'

module Naught::NullClassBuilder::Commands
  class Traceable < Naught::NullClassBuilder::Command
    def call
      defer do |subject|
        subject.module_eval do
          attr_reader :__file__, :__line__

          def initialize(options={})
            backtrace = if RUBY_VERSION.to_f == 1.9
              options.fetch(:caller) { Kernel.caller(4) }
            else
              options.fetch(:caller) { Kernel.caller(3) }
            end
            @__file__, line, _ = backtrace[0].split(':')
            @__line__ = line.to_i
          end
        end
      end
    end
  end
end
```
assistant