222 Chapter 8: Creating a Manipulator
Creating a New Manipulator iTool Developer’s Guide
PRO ExampleManip::SetProperty, _REF_EXTRA = _extra
IF (N_ELEMENTS(_extra) GT 0) THEN $
self->IDLitManipulator::SetProperty, _EXTRA = _extra
END
Discussion
The GetProperty and SetProperty methods first define the keywords they will accept.
There must be a keyword for each property of the manipulator type. The keyword
inheritance mechanism allows properties to be retrieved from or set on the
ExampleManip class’ superclasses without knowing the names of the properties.
In this example, there are no properties specific to the
ExampleManip object, so we
simply use the N_ELEMENTS function to check whether the
_extra structure
contains any elements. If it does, we call the superclass’ GetProperty and SetProperty
methods, passing in all of the keywords stored in the
_extra structure.
