Qt接口或抽象类和qobject_cast（）

问题描述

我有一个相当复杂的C ++类，从Java重写。所以每个类都有一个继承的类，然后它也实现一个或多个抽象类（或接口）。

I have a fairly complex set of C++ classes that are re-written from Java. So each class has a single inherited class, and then it also implements one or more abstract classes (or interfaces).

可以使用 qobject_cast（）从类转换到其中一个接口？如果我从 QObject 中导出所有接口，由于不明确的 QObject 引用，我得到一个错误。然而，如果我只有基类继承自 QObject ，我不能使用 qobject_cast（）与 QObject s。

Is it possible to use qobject_cast() to convert from a class to one of the interfaces? If I derive all interfaces from QObject, I get an error due to ambiguous QObject references. If however, I only have the base class inherited from QObject, I can't use qobject_cast() because that operates with QObjects.

我想能够在插件和DLL之间引用

I'd like to be able to throw around classes between plugins and DLLs referred to by their interfaces.

推荐答案

经过一些研究和阅读，我发现：

After some research and reading the qobject_cast documentation, I found this:

这是指向示例的链接：。

Here is the link to the example: Plug & Paint.

挖掘，我发现了宏

首先，不要继承 QObject 从您的接口。对于每个接口，使用Q_DECLARE_INTERFACE声明如下：

First, do not inherit QObject from your interfaces. For every interface you have, use the Q_DECLARE_INTERFACE declaration like this:

class YourInterface
{
public:
    virtual void someAbstractMethod() = 0;
};

Q_DECLARE_INTERFACE(YourInterface, "Timothy.YourInterface/1.0")

在类定义中，使用宏，如下所示：

Then in your class definition, use the Q_INTERFACES macro, like this:

class YourClass: public QObject, public YourInterface, public OtherInterface
{
    Q_OBJECT
    Q_INTERFACES(YourInterface OtherInterface)

public:
    YourClass();

    //...
};

经过所有这些麻烦，以下代码工作：

After all this trouble, the following code works:

YourClass *c = new YourClass();
YourInterface *i = qobject_cast<YourInterface*>(c);
if (i != NULL)
{
    // Yes, c inherits YourInterface
}

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