title: How to execute a variable function that has a default input
body: <p>I have a scheduler something like</p>
  
  <pre><code>$schedule-&gt;command('foo')
            -&gt;weekdays()
            -&gt;hourly()
            -&gt;timezone('America/Chicago')
            -&gt;between('8:00', '17:00');
  </code></pre>
  
  <p>I would like to store <strong>->between('8:00', '17:00');</strong> in my database so that I can always change it. Later on for example I can use rather          <strong>->at('02:00')</strong> ( just example ).</p>
  
  <p>I know that with PHP7 we can use variable functions better than every something like </p>
  
  <p><a href="http://php.net/manual/en/functions.variable-functions.php" rel="nofollow noreferrer">http://php.net/manual/en/functions.variable-functions.php</a></p>
  
  <pre><code>&lt;?php
  
  function sound_dog()() { return 'woof'; }
  function sound_cow()() { return 'moo'; }
  
  $animal = 'cow';
  print ('sound_' . $animal)();
  </code></pre>
  
  <p>But when I want to have an default input inside <strong>('anything at all')</strong> it doesn't work. All examples assumes that there is no default input.</p>
  
  <p>How can I make a variable function that has input inside itself?</p>