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DERIVED
The DERIVED attribute of a PROCEDURE prototype specifies that the PROCEDURE on whose prototype it is placed is a VIRTUAL procedure. It can be used by itself or in addition to the VIRTUAL attribute on the prototype.
Use DERIVED to force a compile error when non-matching prototypes between a DERIVED virtual method and its PARENT are found. This prevents function overloading when a VIRTUAL method is the intention.
Example:
ClassA CLASS
Method1 PROCEDURE(LONG, <;LONG>),VIRTUAL
END
ClassB CLASS(ClassA)
Method1 PROCEDURE(LONG,<;LONG>),DERIVED
END
ClassC CLASS(ClassA)
Method1 PROCEDURE(LONG,<;LONG>),VIRTUAL,DERIVED
END
ClassD CLASS(ClassA)
Method1 PROCEDURE(STRING),DERIVED !Will produce compiler error:
END !must match parent prototype
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