Release 10.1A: OpenEdge Getting Started:
Object-oriented Programming

Calling a super class method

You can invoke the super class definition of a method using the SUPER system reference. Executing a super class method using the SUPER system reference within a subclass causes control to switch to the version of the method in the next higher super class that implements it, bypassing any classes that do not implement the method. The SUPER system reference is normally used to invoke the super class behavior for a method from within the subclass override of that method, in order to construct a chain of behavior. However, it can also be used to invoke any other method in a super class. Therefore, the method name to invoke is part of the syntax.

This is the syntax to call a super class version of a method using the SUPER system reference:

Syntax

[ return-variable = ]     SUPER:method-name ( [ parameter [ , parameter ] ... ] ) .

Element descriptions for this syntax diagram follow:

return-variable

The variable to hold the value returned by the method. If the method is defined with a VOID return type, the method does not return a value and the SUPER system reference does not use the return-variable assignment.

method-name

The name of the method to call in the class hierarchy. The first method found, starting from the immediate super class of the current class and searching upward in the class hierarchy, is the method executed. It might be anywhere in the class hierarchy starting from the immediate super class.

The method invoked can be any method name valid in the class hierarchy. It does not need to match the method name from where the call is made.

[ parameter [ , parameter ] ... ]

The parameters of the method. For more information on the syntax of parameter, see the “Parameter passing syntax” reference entry in OpenEdge Development: Progress 4GL Reference .

From within a class, any invocation of an overridden method without the use of the SUPER system reference invokes the bottom-most subclass's implementation of the method. From within a class, any invocation of an overridden method with the use of the SUPER system reference invokes the super class's implementation of the method. There is no direct access to the super class's implementation of the overridden method from outside the class.