PHP一个类包含另一个类，反之亦然

在PHP中，我有以下包含层次结构：

Offer in offer.php requires once abstractoperation.php
Demand in demand.php requires once abstractoperation.php
Response in response.php requires once offer.php and demand.php
AbstractOperation in abstractoperation.php requires once response.php

我想将函数getLazyResponses添加到AbstractOperation中，以访问来自报价和需求的响应。在C++中，我将使用前向声明来解决这个问题，但是如何在PHP？

中解决这个问题？ 更新3:

我在每个include之前和之后放置echo，以便调试正在发生的事情

如果我在index.php中使用require_once offer.php，应用程序将输出以下内容：

offer.php: including abstractoperation.php
abstractoperation.php: including response.php
response.php: including offer.php
response.php: included offer.php
response.php: including demand.php
demand.php: including abstractoperation.php
demand.php: included abstractoperation.php
Fatal error: Class 'AbstractOperation' not found in /web/classes/dao/demand.php on line 4

demand.php: including abstractoperation.php
abstractoperation.php: including response.php
response.php: including offer.php
offer.php: including abstractoperation.php
offer.php: included abstractoperation.php

Fatal error: Class 'AbstractOperation' not found in /web/classes/dao/offer.php on line 4

如果我在index.php中使用require_once demand.php，应用程序将输出以下内容：

offer.php: including abstractoperation.php
abstractoperation.php: including response.php
response.php: including offer.php
response.php: included offer.php
response.php: including demand.php
demand.php: including abstractoperation.php
demand.php: included abstractoperation.php
Fatal error: Class 'AbstractOperation' not found in /web/classes/dao/demand.php on line 4

demand.php: including abstractoperation.php
abstractoperation.php: including response.php
response.php: including offer.php
offer.php: including abstractoperation.php
offer.php: included abstractoperation.php

Fatal error: Class 'AbstractOperation' not found in /web/classes/dao/offer.php on line 4

---

如果我删除require_once response.php并放入注释getLazyResponses（因此无法从操作中跟踪响应），一切正常。

您在哪里包含

Demand

类文件？如果

abstractoperation.php

文件与

demand.php

放在同一文件夹中，并不意味着它将被包括在内。默认路径将是放置包含

demand.php

的文件的路径。响应类（file Response.php）中包含demand类（file demand.php）。但由于响应包含在Demand中包含的AbstractOperation中，所以包含中有一个循环。如果您使用

include\u once

，则每个文件将只包含一次。就不会有“包括在内的循环”这样的事情了。我认为问题在于包含路径。将

include_once

替换为

require_once

，并告诉我们您有哪些错误。使用。从代码中删除任何包含的类。替换为require_一次，收到相同的错误：致命错误：在第3行的/web/classes/dao/demand.php中找不到类“AbstractOperation”。奇怪的是，上面所有的类都在同一个目录中