语法错误，意外的“ head”（T_STRING）

Question

我创建了一个用于生成html网页的类。 我现在遇到错误。 我找不到我做错的地方，也许我有错别字，有人可以帮助我吗？ 我将不胜感激。 这是我未声明或未添加的内容。     

 /*Singleton Design Pattern*/
class WEBPAGE{

private $title = "";
private $style = [];

/*Store Head, Body, Footer Content*/
private head = "";
private body = "";
private footer = "";

private function __constructor(){
    $this->$title = "";
    $this->$style = [];
}

private function styleGenerator($style){
    $generated_style = [];
}

private function styleTag($src){
    return '<link rel="stylesheet" href="'.$src.'">';
}

public static function getInstance()
{ 
    if(!self::$instance)
    {
        self::$instance = new self();
    }

    return self::$instance;
}

public function ouput(){
    //styleGenerator($this->$style);
    echo "My blank page";
}

}

?>

Answer 1

在前面添加$符号，但缺少$

private head = "";
private body = "";
private footer = "";

代码应如下

private $head = "";
private $body = "";
private $footer = "";

还要删除$ this-> $ title和$ this-> $ style

的$

private function __constructor(){
    $this->title = "";
    $this->style = [];
}