callfunc函数,及函数传值

<?php

function foo()
{
      echo "\nfoot()";
}

function callfunc($x, $y='')
{
      if($y == '')
      {
            if($x == ''){
                echo "\nempty";
            }else{
                $x();
            }
      }else{
            $y->$x();
      }
}

class cbar
{
     public function fcatch()
     { 
        echo "\nfcatch";
     }

}

$x = '';
callfunc($x);  //empty

$x = "foo";
callfunc($x);  //调用foot()这个函数

$o = new cbar();
$x = 'fcatch';
callfunc($x, $o);  //fcatch
?>