Why does the setter of a VB.NET property require a typed argument and why is it ByVal?

Question

In C#, a property's setter value keyword will automatically be same as the property's type.

For example, in C# ,type of value is string

private string str = string.Empty;
public string MyText 
{
    get { return str; }
    set { str = value; }
}

If we convert this snippet to VB.Net we get

Private str As String = String.Empty
Public Property MyText() As String
    Get
        Return str 
    End Get
    Set(ByVal value As String)
        str = value
    End Set
End Property

Questions

1. Why does set have this line Set(ByVal value As String)? Shouldn't value type automatically be String. This way.

   Private str As String = String.Empty
   Public Property MyText() As String
       Get
           Return str 
       End Get
       Set
           str = value
       End Set
   End Property
   

   What's the use of that?

2. I cannot change BYVal to ByRef (I tried, it gives error), then what's use of that also?

Answer 1

You can omit the (ByVal value As String) part. Visual Studio will keep adding it, but it is not required by either the language nor the compiler.

You can use a parameter name other than value. Also note that since VS2010 SP1, you can omit the ByVal keyword.

---

Example:

Class Test

    Private str As String = String.Empty

    Public Property MyText() As String
        Get
            Return str 
        End Get
        Set
            str = value
        End Set
    End Property

    Public Property MyText2() As String
        Get
            Return str 
        End Get
        Set(something As String)
            str = something
        End Set
    End Property

End Class