A property’s value may itself be an object which exports properties; such an object is known as a composite property, and its properties are called sub-properties.
Property handles for sub-properties may be obtained from the top-level exporting class using getProperty(), with successive sub-property names delimited by a ’.’ character. For example, if a class exports a property textureProps, whose value is a composite property exporting a sub-property called mode, then a handle to the mode property can be obtained from the top-level class using
which has the same effect as
Composite properties should adhere to a couple of rules. First, they should be returned by reference; i.e., the hosting class should return a pointer to the original property, rather than a copy. Secondly, they should implement the CompositeProperty interface. This is an extension of HasProperties with the following methods:
These methods can be easily implemented using local variables to store the relevant information, as in
and similarly for the property information.
The purpose of the CompositeProperty interface is to allow traversal of the composite property tree by the property support code.
The accessor method that sets a composite property within a host should set it’s host and property information. This can be done using using the setPropertyHost and setPropertyInfo methods, as in the following example for a compound property of type TextureProps:
Alternatively, the same thing can be done using the static convenience method PropertyUtils.updateCompositeProperty: