构造类变量

Question

我正在尝试在我的 Web 应用程序的“全局范围”中创建我的类变量，以便在您调用它们时可以轻松地在其他类中使用它们并在整个 Web 应用程序中使用它们。这是我的 Web 应用程序的 Articles 类。

class Articles {

   //  Defined variables that constructs an Article
   private $id
   private $title
   private $summary
   private $content
   private $author

   public function __construct($id, $title, $summary, $content, $author) {
      //  Constructs our Article by default
      $this->id      = $id;
      $this->title   = $title;
      $this->summary = $summary;
      $this->content = $content;
      $this->author  = $author;
   }
}

这是我的 init.php 文件

//  Require the Articles and ArticlesHandler Class
require 'Articles/Articles.php';
require 'Articles/ArticlesHander.php';

如果我需要在 ArticlesHandler 中调用 $title，它是否可以只使用 $title 或者我需要它使用 $this->title 来调用它？还是有更好的方法来做到这一点？

Answer 1

您可以轻松地返回值，将它们保存在变量中并将其声明为全局，例如

public function show() {
    return $this->id;
}

然后在你开始你的课程之后，你可以这样做

$id = $class->show();
global $id;

另一种方法是将类中的变量范围更改为公共

那么你就可以轻松做到以下几点

$id = $class->id;
global $id;

Answer 2

    You need to create an object of the class to access the variables. In your case it will be 

        $articles = new Articles(1,'mytitle','test','mycontent','myauthor');
        echo $articles->title; // mytitle

    If you can give more information on what your ArticlesHandler class is doing, I could edit my answer to your requirements.

**Edit:**

    private variables are meant to be private to the class , so they cannot be accessed outside the class.

    There are different ways to address this:
    1.  create a public function and return the private variable through it. 
    public function displayTitle(){
    return $this->title;
    }

    2. You could make ArticlesHanlder subclass of Articles and make the variables in Articles protected, so it is accessible by the classes that inherit Articles class.
    then you could just use it like $this->title in the ArticlesHanlder.