c++ - QHash 问题

Question

我一直在尝试并试图让它工作，但它就是拒绝工作。我阅读了 QT 文档，但无法使插入功能发挥作用。构建时出现以下复杂错误

/home/mmanley/projects/StreamDesk/libstreamdesk/SDDatabase.cpp: In constructor 'SDDatabase::SDDatabase()':
/home/mmanley/projects/StreamDesk/libstreamdesk/SDDatabase.cpp:27:44: error: no matching function for call to 'QHash<QString, SDChatEmbed>::insert(const char [9], SDChatEmbed (&)())'
/usr/include/qt4/QtCore/qhash.h:751:52: note: candidate is: QHash<Key, T>::iterator         QHash<Key, T>::insert(const Key&, const T&) [with Key = QString, T = SDChatEmbed]
make[2]: *** [libstreamdesk/CMakeFiles/streamdesk.dir/SDDatabase.cpp.o] Error 1
make[1]: *** [libstreamdesk/CMakeFiles/streamdesk.dir/all] Error 2

这是头文件:

class SDStreamEmbed {
        Q_OBJECT
    public:
        SDStreamEmbed();
        SDStreamEmbed(const SDStreamEmbed &other);

        QString FriendlyName() const;

        SDStreamEmbed &operator=(const SDStreamEmbed &other) {return *this;}
        bool operator==(const SDStreamEmbed &other) const {return friendlyName == other.friendlyName;}

    private:
        QString friendlyName;
};

Q_DECLARE_METATYPE(SDStreamEmbed)

inline uint qHash(const SDStreamEmbed &key) {
    return qHash(key.FriendlyName());
}

和实现

SDStreamEmbed::SDStreamEmbed() {

}

SDStreamEmbed::SDStreamEmbed(const SDStreamEmbed& other) {

}

QString SDStreamEmbed::FriendlyName() const {
    return friendlyName;
}

以及我是如何调用它的

SDChatEmbed embedTest();
ChatEmbeds.insert("DemoTest", embedTest);

和ChatEmbeds的定义

QHash<QString, SDStreamEmbed> StreamEmbeds;

Answer 1

替换:

SDChatEmbed embedTest();

与:

SDChatEmbed embedTest;

编译器将第一行解释为函数声明。这在错误消息中可见:它为第二个参数推导出以下类型:

SDChatEmbed (&)()

这是一个函数签名。

我认为您不需要明确的 QString自 QString 以来第一个参数的转换/构造有一个接受 const char* 的构造函数, 以便自动转换。

(有关一些有趣的信息，请参阅 here。)