QtQml.qtqml-referenceexamples-default-example

This example builds on:

• Extending QML - Inheritance and Coercion Example
• Extending QML - Object and List Property Types Example
• Extending QML - Adding Types Example

The Default Property Example is a minor modification of the Extending QML - Inheritance and Coercion Example that simplifies the specification of a BirthdayParty through the use of a default property.

BirthdayParty {
host: Boy {
name: "Bob Jones"
shoeSize: 12
}
Boy { name: "Leo Hodges" }
Boy { name: "Jack Smith" }
Girl { name: "Anne Brown" }
}

Declaring the BirthdayParty Class

The only difference between this example and the last, is the addition of the DefaultProperty class info annotation.

class BirthdayParty : public QObject
{
Q_OBJECT
Q_PROPERTY(Person host READ host WRITE setHost)
Q_PROPERTY(QQmlListProperty<Person> guests READ guests)
Q_CLASSINFO("DefaultProperty", "guests")
public:
BirthdayParty(QObject parent = 0);
Person host() const;
void setHost(Person );
QQmlListProperty<Person> guests();
int guestCount() const;
Person guest(int) const;
private:
Person m_host;
QList<Person *> m_guests;
};

The default property specifies the property to assign to whenever an explicit property is not specified, in the case of the BirthdayParty type the guest property. It is purely a syntactic simplification, the behavior is identical to specifying the property by name, but it can add a more natural feel in many situations. The default property must be either an object or list property.

Running the Example

The main.cpp file in the example includes a simple shell application that loads and runs the QML snippet shown at the beginning of this page.

Files:

• referenceexamples/default/birthdayparty.cpp
• referenceexamples/default/birthdayparty.h
• referenceexamples/default/example.qml
• referenceexamples/default/person.cpp
• referenceexamples/default/person.h
• referenceexamples/default/main.cpp
• referenceexamples/default/default.pro
• referenceexamples/default/default.qrc