Type.Missing Field
.NET Framework 3.0
Represents a missing value in the Type information. This field is read-only.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Assembly: mscorlib (in mscorlib.dll)
Use the Missing field for invocation through reflection to obtain the default value of a parameter. If the Missing field is passed in for a parameter value and there is no default value for that parameter, an ArgumentException is thrown.
The following code example shows the use of the Missing field to invoke a method with its default arguments.
Option Strict Off Imports System Imports System.Reflection Public Class OptionalArg Public Sub MyMethod(ByVal a As Integer, Optional ByVal b As Double = 1.2, Optional ByVal c As Integer = 1) Console.WriteLine("a = " & a & " b = " & b & " c = " & c) End Sub End Class Module module1 Sub main() Dim o As New OptionalArg() Dim t As Type t = GetType(OptionalArg) Dim param As Object() = {10, 20, 30} t.InvokeMember("MyMethod", BindingFlags.Public Or BindingFlags.Instance Or BindingFlags.InvokeMethod Or BindingFlags.OptionalParamBinding, Nothing, o, New Object() {10, 55.3, 12}) t.InvokeMember("MyMethod", BindingFlags.Public Or BindingFlags.Instance Or BindingFlags.InvokeMethod Or BindingFlags.OptionalParamBinding, Nothing, o, New Object() {10, 1.3, Type.Missing}) t.InvokeMember("MyMethod", BindingFlags.Public Or BindingFlags.Instance Or BindingFlags.InvokeMethod Or BindingFlags.OptionalParamBinding, Nothing, o, New Object() {10, Type.Missing, Type.Missing}) End Sub End Module
This code produces the following output:
a = 10 b = 55.3 c = 12
a = 10 b = 1.3 c = 1
a = 10 b = 1.2 c = 1
Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.Community Additions
ADD
Show: