title: Can we define variables in `.tpl` files?
body: <p>In general, if we have a Smarty project we assign variables in <code>.php</code> file, and use the variables in its corresponding .tpl` file.</p>
  
  <p>such as:</p>
  
  <pre><code>$smarty-&gt;assign('foo', 'Foo');  // in .php file
  
  {$foo}  // in .tpl file
  </code></pre>
  
  <p>can we define the variables in <code>.tpl</code>? and if can, is this recommend? 
  and why?</p>