QMetaEnum and strong typed enum

Question

With plain enums I was able to access Q_ENUMS properties and specific, the character represenation of enums, with following code:

// in .h
class EnumClass : public QObject
{
  Q_OBJECT
public:
  enum  MyEnumType { TypeA, TypeB };
  Q_ENUMS(MyEnumType)
private:
  MyEnumType m_type;
};

// in .cpp
m_type = TypeA;
...
const QMetaObject &mo = EnumClass::staticMetaObject;
int index = mo.indexOfEnumerator("MyEnumType");
QMetaEnum metaEnum = mo.enumerator(index);
QString enumString = metaEnum.valueToKey(m_type); // contains "TypeA"

If I want to use the c++11 feature for strong typed enums like

enum class MyEnumType { TypeA, TypeB };

accessing the meta information does not work anymore. I guess, that Qt does not recognize it as an enum anymore.

Is there any solution to access the character represenation of an enum while using strong typed enums?

Answer 1

Q_ENUMS is obsolete, and Q_ENUM should be used instead, but the following code works for me with either of them (Qt 5.5, your issue might be caused by an old Qt version; also this question is relevant):

.h:

#include <QObject>
class EnumClass : public QObject
{
    Q_OBJECT
public:
    enum class MyEnumType { TypeA, TypeB };
    EnumClass();
    Q_ENUM(MyEnumType)
private:
    MyEnumType m_type;
};

.cpp:

#include <QDebug>
#include <QMetaEnum>
#include <QMetaObject>
EnumClass::EnumClass()
{
    m_type = MyEnumType::TypeA;
    const QMetaObject &mo = EnumClass::staticMetaObject;
    int index = mo.indexOfEnumerator("MyEnumType");
    QMetaEnum metaEnum = mo.enumerator(index);
    // note the explicit cast:
    QString enumString = metaEnum.valueToKey(static_cast<int>(m_type));
    qDebug() << enumString;
}

main:

int main()
{
    EnumClass asd;
    return 0;
}

output:

"TypeA"