//! [0]
struct MyStruct
{
    int i;
    ...
};

Q_DECLARE_METATYPE(MyStruct)
//! [0]


//! [1]
namespace MyNamespace
{
    ...
}

Q_DECLARE_METATYPE(MyNamespace::MyStruct)
//! [1]


//! [2]
MyStruct s;
QVariant var;
var.setValue(s); // copy s into the variant

...

// retrieve the value
MyStruct s2 = var.value<MyStruct>();
//! [2]


//! [3]
int id = QMetaType::type("MyClass");
if (id != -1) {
    void *myClassPtr = QMetaType::construct(id);
    ...
    QMetaType::destroy(id, myClassPtr);
    myClassPtr = 0;
}
//! [3]


//! [4]
qRegisterMetaType<MyClass>("MyClass");
//! [4]


//! [5]
qRegisterMetaTypeStreamOperators<MyClass>("MyClass");
//! [5]


//! [6]
QDataStream &operator<<(QDataStream &out, const MyClass &myObj);
QDataStream &operator>>(QDataStream &in, MyClass &myObj);
//! [6]


//! [7]
int id = qRegisterMetaType<MyStruct>();
//! [7]


//! [8]
int id = qMetaTypeId<QString>();    // id is now QMetaType::QString
id = qMetaTypeId<MyStruct>();       // compile error if MyStruct not declared
//! [8]