ByRef vs ByVal Clarification

Question

I\'m just starting on a class to handle client connections to a TCP server. Here is the code I\'ve written thus far:

Imports System.Net.Sockets
Imports Syst         


        

Answer 1

Remember that ByVal still passes references. The difference is that you get a copy of the reference.

So, on my overloaded constructor, I am accepting a reference to an instance of a System.Net.Sockets.Socket, yes?

Yes, but the same would be true if you asked for it ByVal instead. The difference is that with ByVal you get a copy of the reference — you have new variable. With ByRef, it's the same variable.

It is my understanding that the instance in memory is copied

Nope. Only the reference is copied. Therefore, you're still working with the same instance.

Here's a code example that explains it more clearly:

Public Class Foo
   Public Property Bar As String
   Public Sub New(ByVal Bar As String)
       Me.Bar = Bar
   End Sub
End Class

Public Sub RefTest(ByRef Baz As Foo)
     Baz.Bar = "Foo"
     Baz = new Foo("replaced")
End Sub

Public Sub ValTest(ByVal Baz As Foo)
    Baz.Bar = "Foo"
    Baz = new Foo("replaced")
End Sub

Dim MyFoo As New Foo("-")
RefTest(MyFoo)
Console.WriteLine(MyFoo.Bar) ''# outputs replaced

ValTest(MyFoo)
Console.WriteLine(MyFoo.Bar) ''# outputs Foo