c++ - LNK2019 未解析的 QObject 外部符号

Question

使用 QMake 构建时出现以下错误:

• LNK2019: unresolved external symbol "public: void __cdecl TimerTodo::notify(class TodoBaseTask *)" (?notify@TimerTodo@@QEAAXPEAVTodoBaseTask@@@Z) referenced in function "private: void __cdecl TimerTodo::timerOver(void)" (?timerOver@TimerTodo@@AEAAXXZ)

• LNK2019: unresolved external symbol "public: void __cdecl TimerTodo::hasNotified(class TimerTodo *)" (?hasNotified@TimerTodo@@QEAAXPEAV1@@Z) referenced in function "private: void __cdecl TimerTodo::timerOver(void)" (?timerOver@TimerTodo@@AEAAXXZ)

• LNK1120: 2 unresolved externals

这是我的标题:

#ifndef TIMERTODO_H
#define TIMERTODO_H

#include <QTimer>

class TodoBaseTask;

class TimerTodo : public QTimer
{
public:
    TimerTodo(TodoBaseTask *timer);
    void StartTimer();
private slots:
    void timerOver();
signals:
    void notify(TodoBaseTask *todo);
    void hasNotified(TimerTodo *timer);
private:
    TodoBaseTask *m_todo;
};

#endif // TIMERTODO_H

这是我的来源:

#include "timertodo.h"
#include "todobasetask.h"

TimerTodo::TimerTodo(TodoBaseTask *todo)
{
    m_todo = todo;
    connect(this, SIGNAL(timeout()), this, SLOT(timerOver()));
}

void TimerTodo::StartTimer()
{
    QDateTime nextNotify = m_todo->getDeadLine().addDays(-1);
    this->start(QDateTime::currentDateTime().msecsTo(nextNotify));
}

void TimerTodo::timerOver()
{
    emit notify(m_todo);
    emit hasNotified(this);
}

如何解决？

Answer 1

这在 Qt documentation 中有解释:

The moc tool reads a C++ header file. If it finds one or more class declarations that contain the Q_OBJECT macro, it produces a C++ source file containing the meta-object code for those classes. Among other things, meta-object code is required for the signals and slots mechanism, the run-time type information, and the dynamic property system.

(强调我的)

所以你需要把这个宏放在每个有自己的信号或槽的类中。