title: How to delete a table in Lua?
body: <p>Let us see the following codes.</p>
  
  <pre><code>do
      local a = {1,2,3}
      function a:doSth()
          self = nil
      end
  
      a:doSth()
  
      if a then
          print("Still has a...")
      end
  end
  </code></pre>
  
  <p>I found that this method doesn't work. The table <code>a</code> still exists. Why?
  I know the <code>a = nil</code> can reclaim the memory which table <code>a</code> holds.
  How to directly get the memory holds by the table <code>a</code> and free the memory just like <code>delete</code> in C++?</p>