title: ruby: instance_eval a file while maintaining file:line in stacktrace?
body: <p>If I do</p>
  
  <pre><code>def eval_file(file)
    instance_eval read(file)
  end
  </code></pre>
  
  <p>Then once something happens in one of the methods / blocks inside the file all I see is something like <code>(eval):20 in 'eval_file</code>'. When I use eval_file with many files it is hard to tell from which one the exception came (the exception happens after the eval, when using a method)</p>
  
  <p>Is there some way for me to see the actual file and line number?</p>