Cannot put QAbstractListModel object as one class's property

Question

My code looks like so:

class Wrapper: public QObject {
  Q_OBJECT
  Q_PROPERTY(PeopleListModel & list READ list)
public:
  PeopleListModel & list() {
    return list_;
  }  

private:
  PeopleListModel list_;  
};

And PeopleListModel is a subclass of QAbstractListModel.

But I got compilation error:

       ^
In file included from plugin.cpp:131:0:
plugin.moc: In member function ‘virtual int Wrapper::qt_metacall(QMetaObject::Call, int, void**)’:
plugin.moc:184:52: error: cannot declare pointer to ‘class PeopleListModel&’
         case 0: *reinterpret_cast< PeopleListModel&*>(_v) = list(); break;
                                                    ^
In file included from ../../../../Qt5.2.0/5.2.0/gcc_64/include/QtCore/qnamespace.h:45:0,
                 from ../../../../Qt5.2.0/5.2.0/gcc_64/include/QtCore/qobjectdefs.h:45,
                 from ../../../../Qt5.2.0/5.2.0/gcc_64/include/QtCore/qobject.h:48,
                 from ../../../../Qt5.2.0/5.2.0/gcc_64/include/QtCore/qplugin.h:45,
                 from ../../../../Qt5.2.0/5.2.0/gcc_64/include/QtQml/qqmlextensionplugin.h:45,
                 from ../../../../Qt5.2.0/5.2.0/gcc_64/include/QtQml/QQmlExtensionPlugin:1,
                 from plugin.cpp:1:
../../../../Qt5.2.0/5.2.0/gcc_64/include/QtCore/qabstractitemmodel.h: In member function ‘PeopleListModel& PeopleListModel::operator=(const PeopleListModel&)’:
../../../../Qt5.2.0/5.2.0/gcc_64/include/QtCore/qglobal.h:967:12: error: ‘QAbstractListModel& QAbstractListModel::operator=(const QAbstractListModel&)’ is private
     Class &operator=(const Class &) Q_DECL_EQ_DELETE;
            ^
../../../../Qt5.2.0/5.2.0/gcc_64/include/QtCore/qabstractitemmodel.h:479:5: note: in expansion of macro ‘Q_DISABLE_COPY’
     Q_DISABLE_COPY(QAbstractListModel)
     ^
plugin.cpp:32:7: error: within this context
 class PeopleListModel : public QAbstractListModel {
       ^
In file included from plugin.cpp:131:0:
plugin.moc: In member function ‘virtual int Wrapper::qt_metacall(QMetaObject::Call, int, void**)’:
plugin.moc:184:59: note: synthesized method ‘PeopleListModel& PeopleListModel::operator=(const PeopleListModel&)’ first required here 
         case 0: *reinterpret_cast< PeopleListModel&*>(_v) = list(); break;
                                                           ^
make: *** [plugin.o] Error 1