“早退”最佳实践和DRY

Question

我想知道在某些情况下是否有更好的方法来“摆脱”方法。让我用代码更好地解释一下：

function execute($context)
{
    // some init actions

    $event = new BeforeOperationOne();
    $this->dispatch($event);
    if ($event->accessGranted()) {
        $context->setUser($this->user);
        // other repeated code

        return;
    }

    $result = $this->operationOne();

    // some other code

    $event = new BeforeOperationTwo();
    $this->dispatch($event);
    if ($event->accessGranted()) {
        $context->setUser($this->user);
        // other repeated code

        return;
    }

    // this is not important what is access checker, 
    // this is just to show that all following code uses data
    // computed in previous steps
    $accessChecker = new AccessChecker($result);
    $this->operationTwo(accessChecker);

    // some other code

    $event = new BeforeOperationThree();
    $this->dispatch($event);
    if ($event->accessGranted()) {
        $context->setUser($this->user);
        // other repeated code

        return;
    }

    $this->operationThree();

    // some other code
}

我们在这里重复了这个条件，当用户可以从事件访问时，在上下文中设置用户。我能想到的选择是：

1. 丑陋的 do-while(false) 或 goto（我最好保持现在这样）
2. 将此提取到方法并将条件更改为 if (!$this->handleEvent($event, $context)) { return; }- 这没有多大帮助，并且无法认为更好的名称句柄不会说它正在返回一些东西
3. 为操作构建闭包数组并循环检查。我们可以假设所有事件类都派生自具有 accessGranted 方法的公共类。这可能很难看，因为某些操作需要来自先前“步骤”的数据，我必须将它们保留在外面并传递它们。
4. 抛出并捕获用户有权访问的异常 - 另一个糟糕的解决方案。

你有什么想法可以写得更好吗？

Answer 1

@Greg 我正在考虑类似的事情：

abstract class Handler
{
    protected $nextHandler = null;

    abstract public function Request($request);

    public function setNextHandler(Handler $handler)
    {
        $this->nextHandler = $handler;
    }

    protected function someOperations($event)
    {
        //i copied this section, so you must shape that
        $this->dispatch($event);
        if ($event->accessGranted()) {
            $context->setUser($this->user);
            // other repeated code

            return true;
        }

        return false;
    }
}

class BeforeOperationOneHandler extends Handler
{
    public function Request($request)
    {
          if ($this->someOperations(new BeforeOperationOne())) {
              return;
          }

          $result = $this->operationOne(); // shape this too

          return $this->nextHandler->Request($result);
    }
}

class BeforeOperationTwoHandler extends Handler
{
    public function Request($request)
    {
          if ($this->someOperations(new BeforeOperationTwo())) {
              return;
          }

          $accessChecker = new AccessChecker($result); // shape this too
          $result = $this->operationTwo(accessChecker);

          return $this->nextHandler->Request($result);
    }
}

class BeforeOperationThreeHandler extends Handler
{
    public function Request($request)
    {
          if ($this->someOperations(new BeforeOperationThree())) {
              return;
          }

          $result = $this->operationThree(); // shape this too

          return $this->nextHandler->Request($result);
    }
}

class DefaultHandler extends Handler
{
    public function Request($request)
    {
          // this is the last step
    }
}




function execute($context)
{
    // some init actions
    $beforeOperationOneHandler = new BeforeOperationOneHandler();
    $beforeOperationTwoHandler = new BeforeOperationTwoHandler();
    $beforeOperationThreeHandler = new BeforeOperationThreeHandler();
    $defaultHandler = new DefaultHandler();

    // set the sequence of the elements
    // BeforeOperationOneHandler > BeforeOperationTwoHandler > BeforeOperationThreeHandler> DefaultHandler
    $beforeOperationOneHandler->setNextHandler($beforeOperationTwoHandler);
    $beforeOperationTwoHandler->setNextHandler($beforeOperationThreeHandler);
    $beforeOperationThreeHandler->setNextHandler($defaultHandler);

    return $beforeOperationOneHandler->Request($some_init);
}

这只是“责任链”模式的快速编写形式，所以我不假思索地复制了你的一些代码片段
我希望这将引导您找到更好的解决方案