PHP构造函数和静态函数 [英] PHP constructors and static functions

问题描述

我对PHP中的构造函数有些困惑。

I'm a bit confused on how constructors work in PHP.

我有一个类，当我实例化一个新对象时，它会被调用。 p>

I have a class with a constructor which gets called when I instantiate a new object.

$foo = new Foo($args);

__ construct（$ params） Foo 并执行相应的初始化代码。

__construct($params) is called in the class Foo and it executes the appropriate initialization code.

但是当我使用类来调用静态函数，再次调用构造函数。

However when I use the class to call a static function, the constructor is called again.

$bar = Foo::some_function(); //runs the constructor from Foo

这将使构造函数执行，运行对象初始化代码，只有当我创建一个新的 Foo 对象。

This causes the constructor to execute, running the object initialization code that I intended only for when I create a new Foo object.

我缺少构造函数的工作原理吗？或者有一种方法可以防止 __ construct（）在我使用类进行静态函数调用时执行？

Am I missing the point of how constructors work? Or is there a way to prevent __construct() from executing when I use the class to make static function calls?

我应该使用工厂函数来做对象初始化吗？如果是，那么构造函数的要点是什么？

Should I use a "factory" function instead to do the object initialization? If so, what's the point of the constructor then?

:: EDIT ::
我有一个表单，用户可以将照片上传到相册（create_photo。 php）和他们可以查看相册的区域（view_photos.php）。提交表单后：

::: I have a form where users can upload photos to an album (create_photo.php) and an area where they can view the album (view_photos.php). Upon form submit:

$photo = new Photo($_FILES['photo'], $_POST['arg1'], ect..);

Photo构造函数创建并保存照片。但是在view_photo.php中，当我调用：

The Photo constructor creates and saves the photo. However in view_photo.php, when I call:

$photo = Photo::find_by_id($_POST['id']) //user-defined function to query database

这是Photo的构造函数的运行方式！

This is causing Photo's constructor to run!

推荐答案

我看不到有什么复制你的问题。

I see nothing that replicates your question.

查看演示： http://codepad.org/h2TMPYUV

代码：

class Foo {
    function __construct(){ 
        echo 'hi!';
    }
    static function bar(){
        return 'there';
    }
}

echo Foo::bar(); //output: "there"

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