如何将属性声明为限制为继承基类的类的泛型类型？

Question

Update1: It was kind of a duplicate before this update, but I think now it's specific enough and the duplicate doesn't answer this edited question at all. Ok, so I found out that I must use a Generic Class with constraints. The problem still remains about how can I constrain only to classes derived from a class.

Practically, I want to be able to declare some kind of abstract property, with a type declared in a derived class, but limited only to derived types declared in the original class. Let's take this example:

Public Class ObjectBase
End Class

Public Class Derived1Class
inherits ObjectClass
Public Property1 as String
End Class

Public class Derived2Class
inherits ObjectClass
Public Property2 as string
End Class

Public Class SomeOtherClass(Of T as {OnlyClassesWhichInherits(ObjectBase)})
Public Property SomeProperty as T
End Class

Public Class SomeOtherDerivedClass
inherits SomeOtherClass
Sub New()
SomeProperty = New Derived1Class
SomeProperty.Property1:="this should be valid"
End Sub
End Class

The only way I know so that this can be accomplished is by declaring SomeProperty as Object(Update1:now I now this feature is named generic classes). If I declare SomeProperty as ObjectBase, the compiler has no problem with SomeProperty=New DerivedClass, but it complains that Property1 is not a member of ObjectBase, which is true, but still, it works with SomeProperty as Object. This means the kind of behaviour I'm interested in already exists in .NET and it's implemented in Object class(Update1: Generic Classes).

How to write a constraint to derived classes of ObjecBase?

Answer 1

Public Class SomeOtherClass(Of T as {OnlyClassesWhichInherits(ObjectBase)})

Are you perhaps looking for… this? :)

Public Class SomeOtherClass(Of T As ObjectBase)