还可以是字典，

public function index(){
    $new = $this->index_com();
    //输出指定的值
    echo $new[list];
}

public function index_com(){
    $list       = 'a';
    $category   = 'b';
    $totalCount = 'c';
    $current    = 'd';
    return array('list'=>$list, 'category'=>$category);
}

public function index(){
    $new = $this->index_com($k);
    //输出指定的值
    echo $new;
}
public function index_com($k){
    $arr=['list'=>a,'category'=>'c'];
    return $arr[$k];

使用list语法可以达到你想要的效果：

public function index(){
   list($list, $category, $totalCount, $current) = $this->index_com();
   //输出指定的值
   echo $category;
}

public function index_com(){
    $list = 'a';
    $category = 'b';
    $totalCount = 'c';
    $current = 'd';
    return array($list, $category, $totalCount, $current);
}