PHP [OOP] - 如何手动调用类构造函数？ [英] PHP[OOP] - How to call class constructor manually?

问题描述

请参阅下面的代码：

  01。 class Test {
 02. public function __construct（$ param1，$ param2，$ param3）{
 03. echo $ param1。$ param2。$ param3; 
 04.} 
 05.} 
 06. 
 07. $ params = array（'p1'，'p2'，'p3'）; 
 08. 
 09. $ ob = new Test; 
 10. 
 11. if（method_exists（$ ob，'__ construct'））{
 12. call_user_func_array（array（$ ob，'__ construct'），$ params）; 
 13.} 
  

现在，问题是在第09行调用

$ <$ p

有可能吗？如果那么如何？

解决方案

这是不可能防止构造函数被调用时的对象构造（代码中的第9行）。如果在你的 __ construct（）方法中发生了一些你希望推迟到构造之后的函数，你应该把它移动到另一个方法。该方法的好名字可能是 init（）。

为什么不这样做？

  class Test {
 public function __construct（$ param1，$ param2，$ param3）{
 echo $ param1 $ param2。$ param3; 
} 
} 
 
 $ ob = new Test（'p1'，'p2'，'p3'）; 
  

编辑：我只是想一个hacky方式，你可以防止构造函数被调用。您可以子类 Test ，并用一个空的无用的构造函数覆盖构造函数。

  class SubTest extends Test {
 public function __construct（）{
 //不调用parent :: __ construct（）
} 
 
 public function init（$ param1，$ param2，$ param3）{
 parent :: __ construct（$ param1，$ param2，$ param3）; 
} 
} 
 
 $ ob = new SubTest（）; 
 $ ob-> init（'p1'，'p2'，'p3'）; 
  

这可能是有意义的，如果你处理一些代码，需要解决编写不良的构造函数的一些恼人的行为。

Please see the code bellow:

01. class Test {
02.     public function __construct($param1, $param2, $param3) {
03.         echo $param1.$param2.$param3;
04.     }
05. }
06. 
07. $params = array('p1','p2','p3');
08. 
09. $ob = new Test;
10. 
11. if(method_exists($ob,'__construct')) {
12.     call_user_func_array(array($ob,'__construct'),$params);
13. }

Now, the problem is the constructor is called in line 09

But i want to call it manually at line 11-13

Is it possible? If then how? Any idea please?

解决方案

It is not possible to prevent the constructor from being called when the object is constructed (line 9 in your code). If there is some functionality that happens in your __construct() method that you wish to postpone until after construction, you should move it to another method. A good name for that method might be init().

Why not just do this?

class Test {
    public function __construct($param1, $param2, $param3) {
        echo $param1.$param2.$param3;
    }
}

$ob = new Test('p1', 'p2', 'p3');

EDIT: I just thought of a hacky way you could prevent a constructor from being called (sort of). You could subclass Test and override the constructor with an empty, do-nothing constructor.

class SubTest extends Test {
    public function __construct() {
        // don't call parent::__construct()
    }

    public function init($param1, $param2, $param3) {
        parent::__construct($param1, $param2, $param3);
    }
}

$ob = new SubTest();
$ob->init('p1', 'p2', 'p3');

This is might make sense if you're dealing with some code that you cannot change for some reason and need to work around some annoying behavior of a poorly written constructor.

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