IsA( ) method

Returns TRUE if a class or interface represented by the Progress.Lang.Class object or object type-name expression passed to the method is in the hierarchy of the Progress.Lang.Class class instance on which the method is called. Otherwise, the method returns FALSE. The IsA( ) method supports the reflection capabilities of the Progress.Lang.Class class.

Return type: LOGICAL

Access: PUBLIC

Applies to: Progress.Lang.Class class

Syntax

IsA ( { INPUT object-reference AS Progress.Lang.Class |
         INPUT object-type-name AS CHARACTER } )

object-reference

An object reference to a Progress.Lang.Class instance that can represent a class or interface type.

object-type-name

A CHARACTER expression that evaluates to a class or interface type name.

This method returns TRUE when the Progress.Lang.Class class instance on which the method is called represents a class type that:

• Is the same class represented by the Progress.Lang.Class object or class type-name expression passed to the method.
• Derives from (is a subclass of) the class represented by the Progress.Lang.Class object or class type-name expression passed to the method.
• Implements the interface represented by the Progress.Lang.Class object or interface type-name expression passed to the method. The passed interface type can be a super interface in the hierarchy of an interface that is implemented by the class type represented by the Progress.Lang.Class class on which the method is called.

In this example, the IsA( ) method is used to determine if a "Customer" object is within the hierarchy of a "Bar" class. Note that "Customer" can represent either a class type or an interface type.

DEFINE VARIABLE b        AS LOGICAL             NO-UNDO.
DEFINE VARIABLE barType  AS Progress.Lang.Class NO-UNDO.
DEFINE VARIABLE custType AS Progress.Lang.Class NO-UNDO.

/* Determines if a "Customer" class object is within the hierarchy of
   a "Bar" class */
ASSIGN
  barType  = Progress.Lang.Class:GetClass("Bar")
  custType = Progress.Lang.Class:GetClass("Customer").

b = barType:IsA(custType).
/* or */
b = barType:IsA("Customer").