int id = QMetaType::type("MyClass");
if (id != 0) {
    void *myClassPtr = QMetaType::construct(id);
    ...
    QMetaType::destroy(id, myClassPtr);
    myClassPtr = 0;
}

Member Function Documentation

[static] void * QMetaType::construct(int type, const void * copy = 0)

Returns a copy of copy, assuming it is of type type. If copy is zero, creates a default type.

See also destroy(), isRegistered(), and Type.

[static] void QMetaType::destroy(int type, void * data)

Destroys the data, assuming it is of the type given.

See also construct(), isRegistered(), and Type.

[static] bool QMetaType::isRegistered(int type)

Returns true if the datatype with ID type is registered; otherwise returns false.

See also type(), typeName(), and Type.

[static] bool QMetaType::load(QDataStream & stream, int type, void * data)

Reads the object of the specified type from the given stream into data. Returns true if the object is loaded successfully; otherwise returns false.

The type must have been registered with qRegisterMetaType() and qRegisterMetaTypeStreamOperators() beforehand.

Normally, you should not need to call this function directly. Instead, use QVariant's operator>>(), which relies on load() to stream custom types.

See also save() and qRegisterMetaTypeStreamOperators().

[static] bool QMetaType::save(QDataStream & stream, int type, const void * data)

Writes the object pointed to by data with the ID type to the given stream. Returns true if the object is saved successfully; otherwise returns false.

The type must have been registered with qRegisterMetaType() and qRegisterMetaTypeStreamOperators() beforehand.

Normally, you should not need to call this function directly. Instead, use QVariant's operator<<(), which relies on save() to stream custom types.

See also load() and qRegisterMetaTypeStreamOperators().

[static] int QMetaType::type(const char * typeName)

Returns a handle to the type called typeName, or 0 if there is no such type.

See also isRegistered(), typeName(), and Type.

[static] const char * QMetaType::typeName(int type)

Returns the type name associated with the given type, or 0 if no matching type was found. The returned pointer must not be deleted.

See also type(), isRegistered(), and Type.

[static] void QMetaType::unregisterType(const char * typeName)

Unregisters a user type, with typeName.

This function was introduced in Qt 4.4.

See also type() and typeName().

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

qRegisterMetaType<MyClass>("MyClass");

typedef QString CustomString;
qRegisterMetaType<CustomString>("CustomString");

int id = qRegisterMetaType<MyStruct>();

qRegisterMetaTypeStreamOperators<MyClass>("MyClass");

QDataStream &operator<<(QDataStream &out, const MyClass &myObj);
QDataStream &operator>>(QDataStream &in, MyClass &myObj);

struct MyStruct
{
    int i;
    ...
};

Q_DECLARE_METATYPE(MyStruct)

namespace MyNamespace
{
    ...
}

Q_DECLARE_METATYPE(MyNamespace::MyStruct)

MyStruct s;
QVariant var;
var.setValue(s); // copy s into the variant

...

// retrieve the value
MyStruct s2 = var.value<MyStruct>();