'In Main module
Type MyClass(a as int) 'can be any other class type
...
Sub MainSub(x() as MyClass)
Dim res as MyClass
x(0).Initialize
End Sub
...
'In, say, Code module
Sub CodeSub
Dim x(1) as MyClass
CallSub2(Main, "MainSub", x) 'this works
x(0).a = 1
End Sub