在Delphi中是否需要使用GUID？ [英] Are GUIDs necessary to use interfaces in Delphi?

问题描述

官方文件说它们是可选的。我知道COM interop需要每个接口的唯一标识符，但是我看到的每个接口示例都有一个GUID是否与COM一起使用？是否有任何好处包括一个GUID，如果它不会被用于COM？

解决方案

我注意到一些方法例如 支持 （以确定类是否符合特定接口）要求您在使用GUID之前定义GUID。

此页面通过以下信息确认：

注意：SysUtils单元提供一个
重载的函数，称为Supports
，当
类型和实例支持
特定接口时，返回true或false，
GUID。支持功能在
中以Delphi的方式和
运算符使用。显着差异
是支持函数可以将
作为正确的操作数 GUID或
与
GUID 相关联的接口类型，而是和以名称
的类型。有关
的更多信息，请参阅类参考。

这里有一些有关界面的有趣信息，其中指出：

为什么界面需要
唯一标识？答案是
简单：因为Delphi类可以
实现多个接口。当一个
应用程序正在运行时，必须有
是一个机制，将
的指针从
实现中获取到适当的接口。 找到
的唯一方法是，如果一个对象实现
接口，并获得一个指向
的指针，该接口的实现是
通过GUIDs 。 / p>

以两个引号加重。

阅读整篇文章也让您意识到 QueryInterface （需要GUID）在幕后使用，原因如引用计数。

The official documentation says they are optional. I know COM interop requires a unique identifier for each interface but every interface example I see has a GUID whether it's used with COM or not? Is there any benefit to including a GUID if its not going to be used with COM?

解决方案

I've noticed that some methods such as Supports (to determine if a class conforms to a specific interface) require that you define a GUID before you can use them.

This page confirms it with the following information:

Note: The SysUtils unit provides an overloaded function called Supports that returns true or false when class types and instances support a particular interface represented by a GUID. The Supports function is used in the manner of the Delphi is and as operators. The significant difference is that the Supports function can take as the right operand either a GUID or an interface type associated with a GUID, whereas is and as take the name of a type. For more information about is and as, see Class References.

Here's some interesting information about interfaces, which states:

Why does an interface need to be uniquely identifiable? The answer is simple: because Delphi classes can implement multiple interfaces. When an application is running, there has to be a mechanism that will get pointer to an appropriate interface from an implementation. The only way to find out if an object implements an interface and to get a pointer to implementation of that interface is through GUIDs.

Emphasis added in both quotes.

Reading this entire article also makes you realize that QueryInterface (which requires a GUID) is used behind the scenes for reasons such as reference counting.

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