PHP：在子类中包装类的所有函数 [英] PHP: Wrap all functions of a class in a subclass

问题描述

使用PHP库类，我想将它的所有公共函数包装在子类中......类似于：

Working with a PHP library class, and I'd like to wrap all of its public functions in a subclass... Something along the lines of:

class BaseClass
{
   function do_something()
   {
        some;
        stuff;
   }

   function do_something_else()
   {
        other;
        stuff;
   }

   /*
    * 20-or-so other functions here!
    */
}

class SubClass extends BaseClass
{
   function magicalOverrideEveryone()
   {
        stuff-to-do-before;        // i.e. Display header
        call_original_function();  // i.e. Display otherwise-undecorated content
        stuff-to-do-after;         // i.e. Display footer
   }
}

将其煮沸，我'如果有一种[有点优雅/干净]的方式在一个地方完成所有操作，我宁愿不必使用相同的包装器代码覆盖每个超类方法。

Boiling it down, I'd prefer not to have to override every superclass method with the same wrapper code, if there's a [somewhat elegant / clean] way to do it all in one place.

是这可能吗？我怀疑我在这里进行元编程，甚至不知道PHP是否提供了这样的野兽，但我想问...

Is this possible? I suspect I'm in metaprogramming land here, and don't even know if PHP offers such a beast, but figured I'd ask...

推荐答案

您可以使用 __ call 魔术方法和一个不直接从基类继承的通用代理类。

You could do this easily with the __call magic method and a generic "proxy" class which doesn't inherit directly from the base class.

这是一个（近）完整的实现一个代理类，它包装你传递它的任何对象。它将在每个方法调用周围调用一些before和after代码。

Here is a (near) complete implementation of a proxying class which wraps whatever object you pass it. It will invoke some "before" and "after" code around each method call.

class MyProxy {
  function __construct($object) {
    $this->object = $object;
  }

  function __call($method, $args) {
    // Run before code here

    // Invoke original method on our proxied object
    call_user_func_array(array($this->object, $method), $args);

    // Run after code here
  }
}


$base = new BaseClass();
$proxy = new MyProxy($base);

$proxy->doSomething(); // invoke $base->doSomething();

您当然希望添加一些错误处理，例如询问代理对象是否响应到 __ call 中的给定方法，如果没有则引发错误。您甚至可以将Proxy类设计为其他代理的基类。子代理类可以在之前实现，在方法之后实现。

You would of course want to add a bit of error handling, like asking the proxied object if it responds to the given method in __call and raising an error if it doesn't. You could even design the Proxy class to be a base-class for other proxies. The child proxy classes could implement before and after methods.

缺点是你的子类不再实现 BaseClass ，这意味着如果你正在使用 type-hinting 并且想要求只传递 BaseClass 类型的对象进入一个函数，这种方法将失败。

The downside is that your "child class" no longer implements BaseClass, meaning if you're using type-hinting and want to demand that only objects of type BaseClass are passed into a function, this approach will fail.

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