Add reference to Class Library at runtime. 3

[Disferente]

How do I use a class library dll that I don't add a reference at design time. I only want to use it if it is selected in the program.

 

[RiverGuy]

Here is an example. I have created a Class Library called SimpleClassLibrary. I've got a single class -- Class1 which contains a single, shared method -- DoSomething. DoSomething simply displays a message box. Here is the code for my class library

Public Class Class1
    Shared Sub DoSomething()
        System.Windows.Forms.MessageBox.Show("hello from SimpleClassLibrary")
    End Sub
End Class

Here is the code for the calling application. When the button is pressed, we should get a messagebox from the .dll.

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim scl As System.Reflection.Assembly = System.Reflection.Assembly.LoadFile("c:\SimpleClassLibrary.dll")
        Dim t As Type = SCL.GetType("SimpleClassLibrary.Class1")
        t.InvokeMember("DoSomething", Reflection.BindingFlags.InvokeMethod, Nothing, Nothing, Nothing)
    End Sub

 

[DaveInIowa]

Great tip RiverGuy! *

 

[Disferente]

Looks like it could be what I need, but I can't get it to work as I need.

Is there any way of invoking non shared members?

 

[RiverGuy]

Try this:

Public Class Class1
    Shared Sub DoSomething()
        System.Windows.Forms.MessageBox.Show("hello from SimpleClassLibrary")
    End Sub
[b]
    Sub DoSomethingElse()
        System.Windows.Forms.MessageBox.Show("hello from SimpleClassLibrary -- instance")
    End Sub[/b]
End Class

Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim scl As System.Reflection.Assembly = System.Reflection.Assembly.LoadFile("c:\SimpleClassLibrary.dll")
        Dim t As Type = SCL.GetType("SimpleClassLibrary.Class1")
        t.InvokeMember("DoSomething", Reflection.BindingFlags.InvokeMethod, Nothing, Nothing, Nothing)
    End Sub
[b]
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim scl As System.Reflection.Assembly = System.Reflection.Assembly.LoadFile("c:\SimpleClassLibrary.dll")
        Dim t As Type = scl.GetType("SimpleClassLibrary.Class1")
        Dim first_instance As Object = scl.CreateInstance("SimpleClassLibrary.Class1")
        t.InvokeMember("DoSomethingElse", Reflection.BindingFlags.InvokeMethod, Nothing, first_instance, Nothing, Nothing)
    End Sub[/b]
End Class

 

[Disferente]

I changed a few things but now it works great.
I am not using InvokeMember at all and I removed the Dim t as type.

Public ClassO as object

Dim scl As System.Reflection.Assembly = System.Reflection.Assembly.LoadFile("C:\MyDll.dll")
Dim obj(1) As Object
obj(0) = "Software\\Something\\Other"
obj(1) = SomeClass
ClassO = scl.CreateInstance("MyDll.Class1", False, Reflection.BindingFlags.InvokeMethod, Nothing, obj, Nothing, Nothing)

Thank you very much for your help.
I use any public variables/procedures/fuctions by
Something=ClassO.Var1
ClassO.SomeSub()


Only problem I have is that I can't put
AddressOf SomeFunction
as a argument to the constructor, but I made a couple of small changes to the Class so I don't really need it anymore.

 

[ousoonerjoe]

River- Nicely done.

To expand on this idea:

If the DLL had a form(s). The parent application is MDI. Is it possible to make the DLL Form(s) a child of the MDI?

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Bluto: What? Over? Did you say "over"? Nothing is over until we decide it is! Was it over when the Germans bombed Pearl Harbor? No!
Otter: Germans?
Boon: Forget it, he's rolling.
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[Disferente]

I don't see why not, the dll I have and use creates tabpages on an existing tabcontrol. I think that would be somewhat similar to MDI.