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**DERIVED**

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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**

**See Also:**

[[class  object declaration .htm|CLASS]]

[[virtual  set virtual method .htm|VIRTUAL]]