Type.DefaultBinder Property

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Source:

Type.cs

Gets a reference to the default binder, which implements internal rules for selecting the appropriate members to be called by InvokeMember(String, BindingFlags, Binder, Object, Object[], ParameterModifier[], CultureInfo, String[]).

public:
 static property System::Reflection::Binder ^ DefaultBinder { System::Reflection::Binder ^ get(); };

public static System.Reflection.Binder DefaultBinder { get; }

static member DefaultBinder : System.Reflection.Binder

Public Shared ReadOnly Property DefaultBinder As Binder

Property Value

Binder

A reference to the default binder used by the system.

Examples

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.

using namespace System;
using namespace System::Reflection;
ref class MyClass
{
public:
   void HelloWorld()
   {
      Console::WriteLine( "Hello World" );
   }

};

int main()
{
   try
   {
      Binder^ defaultBinder = Type::DefaultBinder;
      MyClass^ myClass = gcnew MyClass;
      
      // Invoke the HelloWorld method of MyClass.
      myClass->GetType()->InvokeMember( "HelloWorld", BindingFlags::InvokeMethod, defaultBinder, myClass, nullptr );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "Exception : {0}", e->Message );
   }

}

using System;
using System.Reflection;

public class MyDefaultBinderSample
{
    public static void Main()
    {
        try
        {
            Binder defaultBinder = Type.DefaultBinder;
            MyClass myClass = new MyClass();
            // Invoke the HelloWorld method of MyClass.
            myClass.GetType().InvokeMember("HelloWorld", BindingFlags.InvokeMethod,
                defaultBinder, myClass, new object [] {});
        }
        catch(Exception e)
        {
            Console.WriteLine("Exception :" + e.Message);
        }
    }	

    class MyClass
    {
        public void HelloWorld()
        {
            Console.WriteLine("Hello World");
        }	
    }
}

open System
open System.Reflection

type MyClass() =
    member _.HelloWorld() =
        printfn "Hello World"

try
    let defaultBinder = Type.DefaultBinder
    let myClass = MyClass()
    // Invoke the HelloWorld method of MyClass.
    myClass.GetType().InvokeMember("HelloWorld", BindingFlags.InvokeMethod, defaultBinder, myClass, [||])
    |> ignore
with e ->
    printfn $"Exception: {e.Message}"

Imports System.Reflection

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

    Class [MyClass]

        Public Sub HelloWorld()
            Console.WriteLine("Hello World")
        End Sub
    End Class
End Class

Remarks

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.

See also

• Binder