Q_PROPERTY: the example doesn't work!

[YaK]

I am trying to build the example from documentation, but it fails:

#include <QtCore>
 
#include <iostream>
using namespace std;
 
class MyClass : public QObject
{
	Q_OBJECT
		Q_PROPERTY(Priority priority READ priority WRITE setPriority)
		Q_ENUMS(Priority)
 
public:
	MyClass(QObject *parent = 0)
		:QObject(parent)
	{
 
	};
	~MyClass()
	{
		cout << "MyClass Destructor"<<endl;
	};
 
	enum Priority { High, Low, VeryHigh, VeryLow };
 
	void setPriority(Priority priority);
	Priority priority() const;
};
 
 
int main(int argc, char *argv[])
{
	QCoreApplication a(argc, argv);
	MyClass megaInst;
	return a.exec();
}

#include <QtCore>

#include <iostream>
using namespace std;

class MyClass : public QObject
{
	Q_OBJECT
		Q_PROPERTY(Priority priority READ priority WRITE setPriority)
		Q_ENUMS(Priority)

public:
	MyClass(QObject *parent = 0)
		:QObject(parent)
	{

	};
	~MyClass()
	{
		cout << "MyClass Destructor"<<endl;
	};

	enum Priority { High, Low, VeryHigh, VeryLow };

	void setPriority(Priority priority);
	Priority priority() const;
};


int main(int argc, char *argv[])
{
	QCoreApplication a(argc, argv);
	MyClass megaInst;
	return a.exec();
}

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My VS writes me:

1>main.obj : error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __thiscall MyClass::metaObject(void)const " (?metaObject@MyClass@@UBEPBUQMetaObject@@XZ)
1>main.obj : error LNK2001: unresolved external symbol "public: virtual void * __thiscall MyClass::qt_metacast(char const *)" (?qt_metacast@MyClass@@UAEPAXPBD@Z)
1>main.obj : error LNK2001: unresolved external symbol "public: virtual int __thiscall MyClass::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@MyClass@@UAEHW4Call@QMetaObject@@HPA PAX@Z)

How can it be fixed?

[gsmiko]

Hi!

Exactly, it's just an example, to give you an idea to how it might work.
To make this code compile, put the class in a header file and provide definition for the setPriority and priority functions.
It's not required but it's a good practice to separate declaration from definition, to put the class definition in a separate source file

[wysota]

If you're using QMake then place a "#include main.moc" entry just before the main function, rerun qmake and recompile. By default qmake only scans header files for Q_OBJECT macros.

[savostin]

Hello All,

Could anybody answer me also. Is the Q_PARAMETER the way to do the following:

megaInst.priority = MyClass::VeryHigh;

megaInst.priority = MyClass::VeryHigh;

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or it always have to be

megaInst.setPriority(MyClass::VeryHigh);

megaInst.setPriority(MyClass::VeryHigh);

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(I mean a variable imitation but not function call). If not, what a purpose of Q_PROPERTY if you have to reach property as function?

Or is there any other way to do that?

Thanks