Help: Adding Property to Class that use IMPLEMENTS

[jude7]

Hi..
I have problem using class that use IMPLEMENTS. If i create a new class having interface from other class. The problem is I can't add a new public property or method in it. New property that i write didn't recognized by the instance object.

For example:
I have Interface Class called IHuman, have 3 Properties:
- Name
- DateBirth
- Sex
My Code for Interface Class IHuman:

Public Property Get Name as string
End Property
Public Property Let Name(Byval sData as string)
End Property
 
Public Property Get DateBirth as Date
End Property
Public Property Let DateBirth(Byval dData as Date)
End Property
 
Public Property Get Sex as Integer
End Property
Public Property Let Sex(Byval iData as integer)
End Property

Then I wrote another class called CEmploye that implements IHuman. Beside Name, DateBirth and Sex, i need new property named Salary.
My Code for Class CEmploye:

Implements IHuman
 
Public Property Get Salary as double
End Property
Public Property Let Salary(Byval uData as double)
End Property

My Form's code:

Private Sub Form_Load()
    Dim oEmp as IHuman
    Set oEmp as New CEmploye
 
    oEmp.Name = "Mike"
    oEmp.Sex=0
    oEmp.Salary = 1000   '<--error here
End Sub

Is there any solution(s) to add new method or property to this kind of class ?

Best Regards,
- jude -

[DKenny]

You will need to add the Salary Property to the IHuman Interface, rather than to the CEmployee Class.

[jude7]

Thx...but i wanna get the reusable concept. From IHuman, maybe i'll write CStudent that has no Salary Property, but it has School Property beside Name,Sex and DateBirth...

- jude7 -

You will need to add the Salary Property to the IHuman Interface, rather than to the CEmployee Class.

[Comintern]

Thx...but i wanna get the reusable concept. From IHuman, maybe i'll write CStudent that has no Salary Property, but it has School Property beside Name,Sex and DateBirth...

- jude7 -

The interface -has- to be common to all the shared classes. As you have found out, VB6 doesn't support inheritance. One workaround would be to put all of the properties into the interface class as Declan suggests, but in that class's implementation of the property that is supposed to be 'missing', have it raise a "Method not found" error.

Public Property Get IHuman_Salary() As Double
 
    Call Err.Raise(438, "CEmploye", "Object doesn't support this property or method.")
 
End Property
 
Public Property Let IHuman_Salary(ByVal uData As Double)
 
    Call Err.Raise(438, "CEmploye", "Object doesn't support this property or method.")
 
End Property

It might sound kind of dumb to do it this way, but it will give the same result.

[brucevde]

You cannot reference the different interfaces through the same object variable. Since you declared oEmp as IHuman that interface is all you have access to. Your code should be

Private Sub Form_Load()
    Dim oEmp as CEmploye
    Dim oHuman as IHuman
 
    Set oEmp as New CEmploye
    Set oHuman = oEmp
 
    oHuman .Name = "Mike"
    oHuman .Sex=0
 
    oEmp.Salary = 1000  
 
End Sub