Dynamic Class Creation?

[Ken Myers]

So I am thinking through the first project that I would like to use objects for and hit an immediate road block that I am hoping there is a quick answer to. I have a need to be able to dynamically create classes. So let's say I have a class called Class1 and it implements two interfaces called Interface1 and Interface2. I would like to be able to create 10 instances of the object at runtime each using an interface that I detect at runtime. So my question centers around the following code:

Local oInterface1 As Interface1
Let oInterface1 = Class "Class1"

What if I don't know at compile time whether I will need Interface1 or Interface2? Any ideas how to safely do this or even how to do this at all? The ideal solution would be something like a function I could call that would return an instance of the proper Interface.

Anyone have any ideas or is this simply not possible?

[jcfuller]

Ken,
There may be a couple of different ways depending on how different your class/interfaces are. In this example in the source code forum:

http://www.powerbasic.com/support/pbforums/showthread.php?t=38252

I was a virtual base class and some magic.

Remember also one interface can begat another ( that's a Sunday word isn't it)

If you have more than one interface in your class: oIface2 = oInface1

James

[Ken Myers]

Not Working

I tried to extend what you provided, but I just don't think this is doing what I want it to do. I also tried faking it a number of ways... I think what you are doing will only work if the objects share a common interface...

Sub CreateOne(ByRef MyobjPtr As Dword)
   Dim oMyObj As Interface1
   Let oMyObj = Class "Class1"   
   Poke Dword,VarPtr(MyobjPtr),ObjPtr(oMyObj) 
   If IsNothing(oMyObj) Then 
    MsgBox "not an object",16,"test2"
    Exit Sub
   Else
    MsgBox "it's an object",16,"test3"
   End If         
End Sub

Then a snip from the test code...

    Local iObj As Interface1
    Local myDword As Dword
    CreateOne(ByVal VarPtr(iObj))
    If IsObject(iObj) Then MsgBox "iObj is an object!",16,"test6"       
    VD_StdOut iObj.MyClassMethod(5)

This works, but not if I try to use Interface2...

I'm not sure that what I want to do is possible. Mainly because unless I specify the class for each interface then the methods are not accessible (the compiler complains at compile time).

-Ken

[Ken Myers]

Reflection

I think what I am looking for is something like what I have seen in other OOP languages like java and c#. A possible solution might be reflection. Is there a PB equivalent?

[Edwin Knoppert]

Can not entirly follow but may using it as a dual interface?
And then late bound calls?