A concrete class can have instances stored in the database. In contrast, an abstract class cannot have any instances.
A selection on the Class form determines whether a class is concrete or abstract. On the Class Explorer display, the shape identifies a concrete class.
For all but a few classes, a dash or minus sign (-
) character as the last character in the class name indicates that the class is abstract and can contain other (abstract or concrete) classes. For example, the Rule- class and Work-Cover- class are abstract classes, while Work-Cover-General is a concrete class.
Concrete classes usually appear near or at the bottom (leaf nodes) of the class hierarchy, but may appear anywhere below the top level.
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abstract class, base class, class, directed inheritance, ultimate base class |
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About Class rules
Class hierarchy — Concepts and terms |