Visual Basic .NET Language ByVal and ByRef keywords ByRef keyword
Example
ByRef keyword before method parameter says that parameter will be sent in a way allowing the method to change (assign a new value) the variable underlying the parameter.
Class SomeClass
Public Property Member As Integer
End Class
Module Program
Sub Main()
Dim someInstance As New SomeClass With {.Member = 42}
Foo (someInstance)
' here someInstance is not Nothing
' but someInstance.Member is -42
Bar(someInstance)
' here someInstance is Nothing
End Sub
Sub Foo(ByVal arg As SomeClass)
arg.Member = -arg.Member ' change argument content
arg = Nothing ' change (re-assign) argument
End Sub
Sub Bar(ByRef param As Integer)
arg.Member = -arg.Member ' change argument content
arg = Nothing ' change (re-assign) argument
End Sub
End Module
