__objDerivedFrom()

Template

Function

Name

__objDerivedFrom()

Category

API

Subcategory

Objects

Oneliner

Determine whether a class is derived from another class

Syntax

      __objDerivedFrom( <oObject>,  <xSuper> ) --> lIsParent

Arguments

<oObject> is the object to check.

<xSuper> is the object that may be a parent. <xSuper> can be either an Object or a Character string with the class name.

Returns

__objDerivedFrom() return a logical TRUE (.T.) if <oObject> is derived from <xSuper>.

Description

__objDerivedFrom() is a low level class support function that check is one class is a super class of the other, or in other words, does class <oObject> a child or descendant of <xSuper>.

Examples

      // Create three classes and check their relations

      #include "hbclass.ch"
      PROCEDURE Main()
         LOCAL oSuper,  oObject,  oDress
         oSuper  := TMood():New()
         oObject := THappy():New()
         oDress  := TShirt():New()
         ? __objDerivedFrom( oObject,  oSuper )    // .T.
         ? __objDerivedFrom( oSuper,  oObject )    // .F.
         ? __objDerivedFrom( oObject,  oDress )    // .F.
         RETURN

      CREATE CLASS TMood
         METHOD New() INLINE Self
      ENDCLASS

      CREATE CLASS THappy FROM TMood
         METHOD Smile() INLINE QOut( "*smile*" )
      ENDCLASS

      CREATE CLASS TShirt
         VAR Color
         VAR Size
         METHOD New() INLINE Self
      ENDCLASS

Compliance

Harbour

Files

Library is core

Seealso

__objHasData(), __objHasMethod()