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diff --git a/examples/declarative/referenceexamples/properties/doc/properties.rst b/examples/declarative/referenceexamples/properties/doc/properties.rst new file mode 100644 index 000000000..86c0ef96f --- /dev/null +++ b/examples/declarative/referenceexamples/properties/doc/properties.rst @@ -0,0 +1,89 @@ +_qml-object-and-list-property-types-example: + +Extending QML - Object and List Property Types Example +====================================================== + +Exporting C++ Properties. + +This example builds on :ref:`qml-adding-types-example`. + +The Object and List Property Types example shows how to add object and list +properties in QML. This example adds a BirthdayParty type that specifies a +birthday party, consisting of a celebrant and a list of guests. People are +specified using the People QML type built in the previous example. + +import examples.properties.people + +.. code-block:: javascript: + + BirthdayParty { + host: Person { + name: "Bob Jones" + shoe_size: 12 + } + guests: [ + Person { name: "Leo Hodges" }, + Person { name: "Jack Smith" }, + Person { name: "Anne Brown" } + ] + } + +Declare the BirthdayParty +------------------------- + +The BirthdayParty class is declared like this: + +.. code-block:: python: + + from person import Person + + + # To be used on the @QmlElement decorator + # (QML_IMPORT_MINOR_VERSION is optional) + QML_IMPORT_NAME = "examples.properties.people" + QML_IMPORT_MAJOR_VERSION = 1 + + + @QmlElement + class BirthdayParty(QObject): + + def __init__(self, parent=None): + super().__init__(parent) + self._host = None + self._guests = [] + + @Property(Person) + def host(self): + return self._host + + @host.setter + def host(self, h): + self._host = h + + def guest(self, n): + return self._guests[n] + + def guestCount(self): + return len(self._guests) + + def appendGuest(self, guest): + self._guests.append(guest) + + guests = ListProperty(Person, appendGuest) + +The class contains a member to store the celebrant object, and also a +list member storing the Person instances. + +In QML, the type of a list properties - and the guests property is a list of +people - are all of type ListProperty. ListProperty is simple value +type that contains a set of functions. QML calls these functions +whenever it needs to read from, write to or otherwise interact with +the list. In addition to concrete lists like the people list used in this +example, the use of QQmlListProperty allows for "virtual lists" and other advanced +scenarios. + +Running the Example +------------------- + +The main.py file in the example includes a simple shell application that +loads and runs the QML snippet shown at the beginning of this page. |