title: Creating a new hash with default keys
body: <p>I want to create a hash with an index that comes from an array.</p>
  
  <pre><code>ary = ["a", "b", "c"]
  h = Hash.new(ary.each{|a| h[a] = 0})
  </code></pre>
  
  <p>My goal is to start with a hash like this:</p>
  
  <pre><code>h = {"a"=&gt;0, "b"=&gt;0, "c"=&gt;0}
  </code></pre>
  
  <p>so that later when the hash has changed I can reset it with h.default</p>
  
  <p>Unfortunately the way I'm setting up the hash is not working... any ideas?</p>