(de)serialize enums into QDataStream

datastream_enum.h

#ifndef DATASTREAM_ENUM_H
#define DATASTREAM_ENUM_H

#include <type_traits>


//a function that can serialize any enum into QDataStream
//it stores the enum in a qint64
template<typename Enum,
         typename = typename std::enable_if<std::is_enum<Enum>::value>::type>
QDataStream& operator<<(QDataStream& stream, const Enum& e) {
    stream << static_cast<qint64>(e);
    return stream;
}

//a function that can deserialize any enum from QDataStream
//it reads the enum as if it was stored in qint64
template<typename Enum,
         typename = typename std::enable_if<std::is_enum<Enum>::value>::type>
QDataStream& operator>>(QDataStream& stream, Enum& e) {
    qint64 v;
    stream >> v;
    e = static_cast<Enum>(v);
    return stream;
}


#endif // DATASTREAM_ENUM_H

main.cpp

#include <QtCore>
#include "datastream_enum.h"

//an enum class to test the functions
enum class E : qint32 { V0, V1, V2, V3, V4 };

int main(int argc, char* argv[]) {
    QCoreApplication app(argc, argv);
    QByteArray data;
    //serialization
    QDataStream out(&data, QIODevice::WriteOnly);
    out << E::V1;
    out << E::V3;
   
    //deserialization test
    E e;
    QDataStream in(&data, QIODevice::ReadOnly);
    in >> e;
    Q_ASSERT(e == E::V1);
    in >> e;
    Q_ASSERT(e == E::V3);
    QTimer::singleShot(100, &app, &QCoreApplication::quit);
    return app.exec();
}

thanks!

Since Qt 5.14 no longer needed.

template <typename T>
typename std::enable_if<std::is_enum<T>::value, QDataStream &>::type&
operator<<(QDataStream &s, const T &t)
{ return s << static_cast<typename std::underlying_type<T>::type>(t); }

template <typename T>
typename std::enable_if<std::is_enum<T>::value, QDataStream &>::type&
operator>>(QDataStream &s, T &t)
{ return s >> reinterpret_cast<typename std::underlying_type<T>::type &>(t); }