是否可以使用反射修改对象实例的方法 [英] Is it possible to modify methods of an object instance using reflection

问题描述

我想要做的是用一个普通的旧 PHP 对象创建一个域模型.我正在创建一个库，它将完成所有基础设施的工作.所以我的一个模型看起来像这样

What I'm trying to do is create a domain model with a Plain Old PHP Object. The I'm creating a library which will do all the infrastructure stuff. So one of my models looks like this

class Project {
  public $id;
  public $name;
  public $typeId;

  private $type;

  public function getType() {
    return $this->type;
  }

  public function setType(Type $type) {
    $this->typeId = $type->id;
    $this->type = $type;
  }
}

现在，如果创建一个新项目并使用有效的 Type 对象调用 setType 并使用 ORM 保存项目实例，则项目和类型都会被保存.但是然后我加载项目并使用 getType 方法我希望 ORM 透明地修改了这个方法以从持久性加载对象.所以这个方法在这里:

Now if create a new Project and call setType with a valid Type object and save the project instance using the ORM both the project and type is saved. But then I load the Project and use getType method I want the ORM to have modified this method transparently to load the object from persitence. So this method here:

public function getType() {
  return $this->type;
}

透明地改为:

public function getType() {
  if (is_null($this->type) {
    $this->type = $this->adapter->findById('table', $this->typeId);
  }

  return $this->type; // or return parent::getType();
}

Outlet PHP 使用 eval 为 Project 创建一个名为 Project_Proxy 的代理类，但有时会有 Project 的子类，所以如果有办法，我正在使用 Reflection API 寻找解决方案.

Outlet PHP uses eval to create a Proxy class for Project called Project_Proxy but sometimes there will be subclasses of Project so I am searching for a solution by using Reflection API if there is a way.

我在谷歌上搜索过，但还没有找到改变方法行为的方法

I have search google but haven't found anyway to change a method behaviour

或者使用 Outlet PHP 的 eval 方法为我的模型及其所有子类创建代理类是个好主意吗?

or would it be a good idea to use Outlet PHP's eval method to create Proxy Classes for my models and all subclasses of them?

推荐答案

没有内置的方法可以做到这一点.尽管您可以使用 PECL 扩展名为 runkit 来做到这一点，但我强烈建议您找到另一种解决方案.更改您不知道任何 的函数的实现是非常危险的，并且可能导致错误，在这种情况下，调试单个此类错误可能比编写 if (is_null(...<用于所有函数的/code> 语句.

There is no builtin way of doing this. And although you can do that using the PECL extension called runkit, I would strongly recommend finding another solution. Changing the implementation of functions you can't know anything about is very dangerous and might lead to bugs where debugging a single such bug can take longer than writing the if (is_null(... statements for all your functions.

顺便说一句:不要使用 is_null()，因为您可能会一遍又一遍地从数据库中获取空值.您应该将获取的值存储在单独的变量中.

BTW: don't use is_null(), since you might fetch null values from the database over and over again. You should store the fetched values in a separate variable.

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