title: Dynamically get Object's attribute
body: <p>How do I dynamiclly get an attribute value for an activerecord object?  </p>
  
  <p>for example I have a variable named <code>attr_name</code>.<br>
  I want to do something like this:  </p>
  
  <pre><code>person = Person.find(1)
  attr_name = "address"
  address = person.&lt;function_name&gt;(attr_name)
  </code></pre>
  
  <p>which <code>function_name</code> can be used ?</p>