我需要编辑某人的网站。我需要做的是更改标题。这听起来很容易，但事实并非如此（至少对我而言）。这是相关行的样子：
<title><?php echo Header::instance()->title; ?></title>
Header::什么？我以前从未见过。在其他文件上，我看到了：
<h1 class="title"><?php echo $serial->name; ?></h1>
那是用来显示序列名的。我想用它作为上面的标题，但它说“未定义的变量：串行”。
我该如何改变呢？
You're editing a website made in oop: the header of the page (which should control headers, title and meta I guess) is controlled by a class named Header, which has an instance (get by instance()) and the <title> content is store in its title attribute.
The same scenario occured for the <h1>: an object, stored in the $serial variable has an attribute name which contains the name of the current page.
Header class and edit the title attribute.name attributeFirst block of code (#1) means that you are calling static instance() method of Header class which returns an object containing title property, which is echoed.
Second one echoes name property of $serial object. Thing is, how that variable is passed to the view - you can call static method of any class (#1) anywhere you want, at least when the class is loaded or you have autoloader set up. I assume that view file is require_once()'d or simply in the same file, in that case you need to check where (if anywhere) $serial variable is set and what value it contains.
If you provide more code, I can tell you more things. :)
该类很可能Header被设置为单例。单例是一种设计模式，它只允许一个类的一个实例存在。在 PHP 中，这是通过将__construct方法创建为受保护方法或私有方法来完成的。methid::instance()是一个公共静态方法。因为是静态的，不需要实例化对象就可以调用，静态方法构造了Header。因为该方法是类的一部分，所以它可以访问私有或公共构造函数。在此处查看示例：
简单地::告诉 PHP 你调用了一个静态方法。instance()返回一个实例Header并Header包含一个名为 title 的公共属性，然后用 PHP 回显该属性。
错误的第二个问题。$serial 可能没有在您的代码中定义。