Making enums "setProperty" enabled.

[hickscorp]

Hello,

The code i'm talking about is part of a library. In this context, and in the following lines, the macro RELibOpt will expand to either Q_DECL_EXPORT or Q_DECL_IMPORT depending on what "end" the header is being included.

i have a namespace named RE, containing enums declared like this:

// This trick is to allow the namespace to act as a class for Qt MetaObject stuff.
#ifdef Q_MOC_RUN
class RELibOpt RE {
// To avoid making a heavy Q_OBJECT for the RE namespace.
Q_GADGET
Q_ENUMS	(ReadingDirection /* and other enums... */)
public:
#else
namespace RE {
#endif
	// This gets declared in the generated moc... Very handy trick BTW.
	extern QMetaObject const staticMetaObject;
	// Here comes one of my enum declaration...
	enum ReadingDirection {
		ReadingDirectionUnknown	= 0,
		ReadingDirectionLeftToRight,
		ReadingDirectionRightToLeft,
		ReadingDirectionBottomToTop,
		ReadingDirectionTopToBottom
	};
	// See explaination below for that macro, it doesn't changes anything of the problem anyway.
	RegisterEnumStreamingOperators	(ReadingDirection);
// This is a macro i made to avoid repeating code for each enum i'd like to stream from / to QDataStream.
#define RegisterEnumStreamingOperators(T) \
 static QDataStream& operator<< (QDataStream& s, T const& t) { return s << (qint32)t; }; \
static QDataStream& operator>> (QDataStream& s, T &t) { qint32 q; s >> q; t = (T)q; return s; }
};
Q_DECLARE_METATYPE(RE::ReadingDirection);

// This trick is to allow the namespace to act as a class for Qt MetaObject stuff.
#ifdef Q_MOC_RUN
class RELibOpt RE {
// To avoid making a heavy Q_OBJECT for the RE namespace.
Q_GADGET
Q_ENUMS	(ReadingDirection /* and other enums... */)
public:
#else
namespace RE {
#endif
	// This gets declared in the generated moc... Very handy trick BTW.
	extern QMetaObject const staticMetaObject;
	// Here comes one of my enum declaration...
	enum ReadingDirection {
		ReadingDirectionUnknown	= 0,
		ReadingDirectionLeftToRight,
		ReadingDirectionRightToLeft,
		ReadingDirectionBottomToTop,
		ReadingDirectionTopToBottom
	};
	// See explaination below for that macro, it doesn't changes anything of the problem anyway.
	RegisterEnumStreamingOperators	(ReadingDirection);
// This is a macro i made to avoid repeating code for each enum i'd like to stream from / to QDataStream.
#define RegisterEnumStreamingOperators(T) \
 static QDataStream& operator<< (QDataStream& s, T const& t) { return s << (qint32)t; }; \
static QDataStream& operator>> (QDataStream& s, T &t) { qint32 q; s >> q; t = (T)q; return s; }
};
Q_DECLARE_METATYPE(RE::ReadingDirection);

To copy to clipboard, switch view to plain text mode 

Later on my program (At exec time), i call:

qRegisterMetaTypeStreamOperators<RE::ReadingDirection>("RE::ReadingDirection");
qRegisterMetaType<RE::ReadingDirection>("RE::ReadingDirection")

qRegisterMetaTypeStreamOperators<RE::ReadingDirection>("RE::ReadingDirection");
qRegisterMetaType<RE::ReadingDirection>("RE::ReadingDirection")

To copy to clipboard, switch view to plain text mode 

Then, i have objects using these enums as properties. For instance:

class RELibOpt AnObject : public QObject {
Q_OBJECT
Q_PROPERTY (RE::ReadingDirection readingDirection READ readingDirection WRITE setReadingDirection)
public:
 	// Constructor.
 	Q_INVOKABLE AnObject (QObject *p=0);
 	// Accessors.
 	RE::ReadingDirection const& readingDirection () const { return _readingDirection; }
 	void setReadingDirection (RE::ReadingDirection const &v) { _readingDirection = v; }
};

class RELibOpt AnObject : public QObject {
Q_OBJECT
Q_PROPERTY (RE::ReadingDirection readingDirection READ readingDirection WRITE setReadingDirection)
public:
 	// Constructor.
 	Q_INVOKABLE AnObject (QObject *p=0);
 	// Accessors.
 	RE::ReadingDirection const& readingDirection () const { return _readingDirection; }
 	void setReadingDirection (RE::ReadingDirection const &v) { _readingDirection = v; }
};

To copy to clipboard, switch view to plain text mode 

Using any kind of property setter / getter via QObject::property() / QObject::setProperty() works just fine for everything, but not for my enum types. For instance, doing:

AnObject *obj = new AnObject(this);
obj->setProperty("readingDirection", RE::ReadingDirectionTopToBottom);
// OR, as specified in the docs:
obj->setProperty("readingDirection", "RE::ReadingDirectionTopToBottom");

AnObject *obj = new AnObject(this);
obj->setProperty("readingDirection", RE::ReadingDirectionTopToBottom);
// OR, as specified in the docs:
obj->setProperty("readingDirection", "RE::ReadingDirectionTopToBottom");

To copy to clipboard, switch view to plain text mode 

i have noticed that:

QVariant v = qVariantFromValue(RE::ReadingDirectionBottomToTop);
qDebug() << v.isValid() << v.canConvert<RE::ReadingDirection>() << v;

QVariant v = qVariantFromValue(RE::ReadingDirectionBottomToTop);
qDebug() << v.isValid() << v.canConvert<RE::ReadingDirection>() << v;

To copy to clipboard, switch view to plain text mode 

Gives output:

true true QVariant(RE::ReadingDirection, )

true true QVariant(RE::ReadingDirection, )

To copy to clipboard, switch view to plain text mode 

In other words, the QVariant appears to be valid, but doesn't contain the right value...

Any idea what i'm doing wrong here please?
Thanks for your help,
Pierre.