>>>>Hi,
>>>>
>>>>I have a class defined in a prg file (e.g. MyClass.prg). I need to subclass it so that I can replace the code in one of the methods with my custom code.
>>>>
>>>>How do you do it?
>>>>
>>>>TIA
>>>
>>>Dmitry,
>>>
>>>At the time of the subclass definition, the upper class must be in scope by a SET PROCEDURE TO MyClass.prg. You must create a new prg (assuming you don't want to change the original one) in which you just redefine what needs to be changed.
>>>
>>>For instance, this being MyClass.prg
>>>
>>>

>>>DEFINE CLASS SomeClass AS Custom
>>>
>>>  FUNCTION Method_One
>>>    LPARAMETERS Parm1 AS Number, Parm2 AS Number
>>>    RETURN m.Parm1 * m.Parm2
>>>  ENDFUNC
>>>
>>>  FUNCTION Method_Two
>>>    LPARAMETERS Parm1 AS Number, Parm2 AS Number
>>>    RETURN m.Parm1 / m.Parm2
>>>  ENDFUNC
>>>
>>>END DEFINE
>>>

>>>
>>>you may write a different MySubClass.prg with
>>>
>>>

>>>DEFINE CLASS SomeSubClass AS SomeClass
>>>
>>>  FUNCTION Method_Two
>>>    LPARAMETERS Parm1 AS Number, Parm2 AS Number
>>>    RETURN IIF(m.Parm2 = 0, .NULL., m.Parm1 / m.Parm2)
>>>  ENDFUNC
>>>
>>>END DEFINE
>>>

>>
>>Hi Antonio,
>>
>>If I may ask you a follow up question, please.
>>
>>The class that I am creating, by subclassing, will be used in a Form. And the custom method that will have "my" code will have a reference to the form (e.g. thisform.) Which causes the error.
>>How do I use this subclassed object in the Form so that the custom method would be able to reference the Thisform?
>>
>>UPDATE: I think I need to instantiate the class in the INIT of this method using NewObject().
>
>In my view, the best way to do this is to add a property to your custom class to hold a reference to the containing object. Then either pass that object as a parameter to the Init method or use code to set it.
>
>Init method approach:
>
>

>This.NewObject("mynewobj", "mysubclass", "mysubclass.prg", "", This)
>

>
>and in the subclass's Init method:
>
>

>LPARAMETERS toContainer
>
>IF VARTYPE(m.toContainer) = "O" and NOT ISNULL(m.toContainer)
>   This.oContainer = m.toContainer
>ENDIF 
>...
>

>
>Then, you can refer to the container in subclass code as This.oContainer.
>
>Alternatively:
>
>

>This.NewObject("mynewobj", "mysubclass", "mysubclass.prg")
>This.mynewobj.oContainer = This
>

>
>The reason I think this is the best approach is that it keeps the class self-contained and doesn't rely on any SET anything in setting it up.
>
>Tamar

Thank you for your suggestion and for the sample code.