Question

I’ve seen a lot of chatter on this topic. Though the examples and desired outcomes are always very specific and specialized. Any direction on this is appreciated.

Custom Class:

Public Class customClass(Of T, S)
[include properties]
[include methods]
End Class

Implementation of Class:

dim [string] as string = string.empty
dim [type] as type = [string].gettype 

dim instance as customClass(of [type], integer) 

Also note, I’ve read that vb.net does not allow you to pass parameters to its constructor. I refuse to accept that you can’t pass a type to a class and generate objects dependent on the type of that argument. Is the only answer to this a function in the class which returns a list of objects cast to the desired type? Your time is appreciated.

This question is motivated by academic research. The above is “what I am trying to do” thanks.

Answer 1

Kind of hard to see what you’re trying to do, but if I’m reading this right, you’re trying to take a variable and use that as the generic argument. This is not possible in .NET – when you declare a variable of a generic class, you need a compile-time type as the generic argument, so it cannot be the a variable of type Type.

This is important for a couple of reasons, one of which is to ensure that type constraints are met.

So:

Class Foo(Of T)
End Class

Dim x as Type = GetType(String)
Dim y as Foo(Of x)

does not work – you have to do:

Dim y as Foo(Of String)

There’s always reflection and expression trees, but that’s more of a hack than a solution.