Type.DefaultBinder Property

 

Gets a reference to the default binder, which implements internal rules for selecting the appropriate members to be called by InvokeMember.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

Public Shared ReadOnly Property DefaultBinder As Binder

Property Value

Type: System.Reflection.Binder

A reference to the default binder used by the system.

The default binder provided with the common language runtime is applicable in all but the most specialized circumstances. If you need a binder that follows rules that differ from those of the supplied default binder, define a type derived from the Binder class and pass an instance of that type using the binder parameter of one of the InvokeMember overloads.

Reflection models the accessibility rules of the common type system. For example, if the caller is in the same assembly, the caller does not need special permissions for internal members. Otherwise, the caller needs ReflectionPermission. This is consistent with lookup of members that are protected, private, and so on.

The general principle is that ChangeType should perform only widening conversions, which never lose data. An example of a widening conversion is converting a value that is a 32-bit signed integer to a value that is a 64-bit signed integer. This is distinguished from a narrowing conversion, which may lose data. An example of a narrowing conversion is converting a 64-bit signed integer to a 32-bit signed integer.

The following table lists the conversions supported by the default binder.

Source Type

Target Type

Any type

Its base type.

Any type

The interface it implements.

Char

Unt16, UInt32, Int32, UInt64, Int64, Single, Double

Byte

Char, Unt16, Int16, UInt32, Int32, UInt64, Int64, Single, Double

SByte

Int16, Int32, Int64, Single, Double

UInt16

UInt32, Int32, UInt64, Int64, Single, Double

Int16

Int32, Int64, Single, Double

UInt32

UInt64, Int64, Single, Double

Int32

Int64, Single, Double

UInt64

Single, Double

Int64

Single, Double

Single

Double

Non-reference

By-reference.

The following example gets the default binder from the DefaultBinder property, and invokes a member of MyClass by passing the DefaultBinder value as a parameter to InvokeMember.

Imports System
Imports System.Reflection
Imports Microsoft.VisualBasic

Public Class MyDefaultBinderSample
    Public Shared Sub Main()
        Try
            Dim defaultBinder As Binder = Type.DefaultBinder
            Dim [myClass] As New [MyClass]()
            ' Invoke the HelloWorld method of MyClass.
            [myClass].GetType().InvokeMember("HelloWorld", BindingFlags.InvokeMethod, defaultBinder, [myClass], New Object() {})
        Catch e As Exception
            Console.WriteLine("Exception :" + e.Message.ToString())
        End Try
    End Sub 'Main

    Class [MyClass]

        Public Sub HelloWorld()
            Console.WriteLine("Hello World")
        End Sub 'HelloWorld
    End Class '[MyClass]
End Class 'MyDefaultBinderSample 

.NET Framework
Available since 1.1
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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