c++类静态成员初始化

Question

我在Ubuntu Linux 12.04 LTS上使用Qt 5.2.1。下面是我的类(.h)的定义:

class RtNamedInstance
{
    // [... other code here ...]
public:
    static int _nextInstanceNumber;
    static QMutex _syncObj;
};

这里是我的实现(.cpp):

#include "rtnamedinstance.h"
// Initialize static members
int RtNamedInstance::_nextInstanceNumber = 0;
QMutex RtNamedInstance::_syncObj(QMutex::Recursive);
RtNamedInstance::RtNamedInstance(QString instanceName)
{
    QMutexLocker(&_syncObj);    // (*)
    // [... other code here ...]
}

编译器退出，并在标记为(*)的行上出现以下错误:

rtnamedinstance.cpp: In构造函数"RtNamedInstance:: RtNamedInstance (QString)":rtnamedinstance.cpp: 27:错误:'_syncObj'声明为引用但未初始化

我错过了什么?

Answer 1

根据@JoachimPileborg的建议，我只是忘记键入QMutexLocker变量名称…这让编译器很困惑…

正确的代码是(.cpp):

#include "rtnamedinstance.h"
// Initialize static members
int RtNamedInstance::_nextInstanceNumber = 0;
QMutex RtNamedInstance::_syncObj(QMutex::Recursive);
RtNamedInstance::RtNamedInstance(QString instanceName)
{
    QMutexLocker locker(&_syncObj);
    // [... other code here ...]
}