Question

Rather than giving the very specific case (which I did earlier), let me give a general example. Let’s say that I have a function, called callingFunction. It has one parameter, called parameter. Parameter is of an unknown type. Let us then say that I wish to copy this parameter, and return it as a new object. For example, in pseudo code, something along the lines of…

Function callingFunction(ByVal parameter As Object) As Object

    Dim newObj As New Object

    'newObj has the same value as parameter, but is a distinctly different object
    'with a different reference

    newObj = parameter

    return newObj

End Function

EDIT: Additional Information

The first time I posted this question, I received only one response – I felt that perhaps I made the question too specific. I guess I will explain more, perhaps that will help. I have an ASP page with 10 tables on it. I am trying, using the VB code behind, to come up with a single solution to add new rows to any table. When the user clicks a button, a generic “add row” function should be called.

The difficulty lies in the fact that I have no guarantee of the contents of any table. A new row will have the same contents as the row above it, but given that there are 10 tables, 1 row could contain any number of objects – text boxes, check boxes, etc. So I want to create a generic object, make it of the same type as the row above it, then add it to a new cell, then to a new row, then to the table.

I’ve tested it thoroughly, and the only part my code is failing on lies in this dynamic generation of an object type. Hence why I asked about copying objects. Neither of the solutions posted so far work correctly, by the way. Thank you for your help so far, perhaps this additional information will make it easier to provide advice?

Answer 1

You can’t do this in general. And it won’t be a good idea, for example, if parameter is of a type which implements the singleton pattern. If parameter is of a type which supports copying, it should implement the ICloneable interface. So, your function could look like this:

Function MyFunc(ByVal parameter As Object) As Object
    Dim cloneableObject As ICloneable = TryCast(parameter, ICloneable)
    If Not cloneableObject Is Nothing Then
        Return cloneableObject.Clone()
    Else
        Return Nothing
    End If
End Function