Public vs. Public Shared (Function/Sub) When Invoking DLL...

[xblshun]

Hey guys, I have a DLL I'm using in a project, it's in the resources of the application. I'm getting errors when trying to Invoke it, that's why I'm here posting this thread. Does the Function/Sub I'm trying to call, have to be Shared or does it have to be just Public?!

I believe from the error I'm getting, that is has to be Shared. Reason I say that is the error says somthing along the lines of....

An exception has been thrown by the target of invocation, System.Reflection.Target.

If it helps, I'm also trying to load the DLL from resources like so....

Assembly.Load(My.Resources.ClsLib).GetType("Clib.Run").GetMethod("Execute").Invoke _
(Nothing, New Object() {Byte_Arg, String_Arg})

Anyway, thanks for any future help guys, peace....

[Shaggy Hiker]

A method, whether in a dll or not, has to be part of something. If it is part of a class, then it can't be called without an instance of the class unless it is Shared. If the function is part of a module, then it might appear that it doesn't have to be Shared, but that's because the Shared is hidden, since all members of a module are quietly turned into Shared members by the compilers. Therefore, if the method you are tying to invoke is a member of a class, then you either need to have an instance of the class, or the method has to be Shared. If the method is in a module, then it is already shared.

[Joacim Andersson]

If it's not a shared method then you first need to create an instance of the class before calling one of the methods.

Dim a As Assembly = Assembly.Load(My.Resources.ClsLib)
Dim o As Object = a.CreateInstance("Clib.Run")
o.GetType().GetMethod("Execute").Invoke(o,  New Object() {Byte_Arg, String_Arg})

However this is a really slow and costly process, why don't you just want to have the assembly distributed as file and have a reference to it in your project? It's a lot faster and safer to do so.