C# 4 and .NET 4

Methods ❘ OC165
' Visual Basic
Public Class MyClass2
Public Sub Foo1(ByVal i as Integer)
End Sub
Public Function Foo(ByVal i As Integer) As Integer
Return 2 * i
End Sub
End Class
// F#
type MyClass as this =
member this.Foo(i : int) : int = i * 2
Parameter modifiers
By default, value types are passed by value, and reference types are passed by reference. If a value type that
is passed as a parameter should be changed within a calling method, with C# you can use the parameter
modifier ref.
C++/CLI defines a managed reference operator %. This operator is similar to the C++ reference operator &
except that % can be used with managed types and the garbage collector can keep track of these objects in
case they are moved within the managed heap.
With Visual Basic, the keyword ByRef is used for passing parameters by reference:
// C#
public class ParameterPassing
{
public void ChangeVal(ref int i)
{
i = 3;
}
}
// C++/CLI
public ref class ParameterPassing
{
public:
int ChangeVal(int% i)
{
i = 3;
}
};
' Visual Basic
Public Class ParameterPassing
Public Sub ChangeVal(ByRef i as Integer)
i = 3
End Sub
End Class
When invoking a method with reference parameters, only the C# language requires you to apply
a parameter modifier. C++/CLI and Visual Basic don’t differentiate calling a method with or without the
parameter modifier. C# has the advantage here because you can immediately see in the calling method that
the parameter values can be changed.
Because of the caller syntax, which is not differentiated, Visual Basic does not allow you to overload
methods just by changing the modifier. The C++/CLI compiler allows you to overload the method just
by changing the modifier, but you cannot compile the caller because the resolved method is ambiguous.
www.it-ebooks.info