PHP：在子类中包装类的所有函数

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 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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