title: PHP convert array entries
body: <p>Hi I have such question.
  I have a php array with 4 entries. And I need to create a CLASS task with them.</p>
  
  <pre><code>$array=array('USER','username','other','test');
  </code></pre>
  
  <p>This I want to use to generate this</p>
  
  <pre><code>    $array[0]::find_by_$array[1]($array[3]); 
  
  it must look as    
      USER::find_by_username(test);
  </code></pre>
  
  <p>How I can convert the array values into this line ?
  What is the correct syntax ?</p>