Extending QML - Default Property Example
Default Property.
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") QML_ELEMENT public: BirthdayParty(QObject *parent = nullptr); 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.