BindingFlags Enumeration

 

Specifies flags that control binding and the way in which the search for members and types is conducted by reflection.

This enumeration has a FlagsAttribute attribute that allows a bitwise combination of its member values.

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

[SerializableAttribute]
[FlagsAttribute]
[ComVisibleAttribute(true)]
public enum class BindingFlags

Member nameDescription
CreateInstance

Specifies that reflection should create an instance of the specified type. Calls the constructor that matches the given arguments. The supplied member name is ignored. If the type of lookup is not specified, (Instance | Public) will apply. It is not possible to call a type initializer.

This flag is passed to an InvokeMember method to invoke a constructor.

DeclaredOnly

Specifies that only members declared at the level of the supplied type's hierarchy should be considered. Inherited members are not considered.

Default

Specifies that no binding flags are defined.

ExactBinding

Specifies that types of the supplied arguments must exactly match the types of the corresponding formal parameters. Reflection throws an exception if the caller supplies a non-null Binder object, since that implies that the caller is supplying BindToXXX implementations that will pick the appropriate method.

FlattenHierarchy

Specifies that public and protected static members up the hierarchy should be returned. Private static members in inherited classes are not returned. Static members include fields, methods, events, and properties. Nested types are not returned.

GetField

Specifies that the value of the specified field should be returned.

This flag is passed to an InvokeMember method to get a field value.

GetProperty

Specifies that the value of the specified property should be returned.

This flag is passed to an InvokeMember method to invoke a property getter.

IgnoreCase

Specifies that the case of the member name should not be considered when binding.

IgnoreReturn

Used in COM interop to specify that the return value of the member can be ignored.

Instance

Specifies that instance members are to be included in the search.

InvokeMethod

Specifies that a method is to be invoked. This must not be a constructor or a type initializer.

This flag is passed to an InvokeMember method to invoke a method.

NonPublic

Specifies that non-public members are to be included in the search.

OptionalParamBinding

Returns the set of members whose parameter count matches the number of supplied arguments. This binding flag is used for methods with parameters that have default values and methods with variable arguments (varargs). This flag should only be used with Type::InvokeMember.

Public

Specifies that public members are to be included in the search.

PutDispProperty

Specifies that the PROPPUT member on a COM object should be invoked. PROPPUT specifies a property-setting function that uses a value. Use PutDispProperty if a property has both PROPPUT and PROPPUTREF and you need to distinguish which one is called.

PutRefDispProperty

Specifies that the PROPPUTREF member on a COM object should be invoked. PROPPUTREF specifies a property-setting function that uses a reference instead of a value. Use PutRefDispProperty if a property has both PROPPUT and PROPPUTREF and you need to distinguish which one is called.

SetField

Specifies that the value of the specified field should be set.

This flag is passed to an InvokeMember method to set a field value.

SetProperty

Specifies that the value of the specified property should be set. For COM properties, specifying this binding flag is equivalent to specifying PutDispProperty and PutRefDispProperty.

This flag is passed to an InvokeMember method to invoke a property setter.

Static

Specifies that static members are to be included in the search.

SuppressChangeType

Not implemented.

These BindingFlags control binding for a great many classes in the System, System.Reflection, and System.Runtime namespaces that invoke, create, get, set, and find members and types.

BindingFlags are used in the following Type methods and other places such as MethodBase::Invoke :

InvokeMember and GetMethod are especially important.

The binding flags can be categorized by how they identify a type member, as listed in the following table.

Identified by Accessibility

Identified by Binding Argument

Identified by Operation

DeclaredOnly

FlattenHierarchy

IgnoreCase

IgnoreReturn

Instance

NonPublic

Public

Static

ExactBinding

OptionalParamBinding

CreateInstance

GetField

SetField

GetProperty

SetProperty

InvokeMethod

PutDispProperty

PutRefDispProperty

System_CAPS_noteNote

You must specify Instance or Static along with Public or NonPublic or no members will be returned.

The following table lists the coercions performed by the default Binder::ChangeType. This table applies especially to the ExactBinding binding flag.

Source Type

Target Type

Any type

Its base type.

Any type

The interface it implements.

Char

UInt16, UInt32, Int32, UInt64, Int64, Single, Double

Byte

Char, UInt16, 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 demonstrates many of the binding flags.

using namespace System;
using namespace System::Collections;
using namespace System::Reflection;
using namespace System::IO;

//namespace BindingFlagsSnippet {
public ref class TestClass
{
public:
   String^ Name;

private:
   array<Object^>^ values;
   int methodCalled;

public:

   property Object^ Item [int]
   {
      Object^ get( int index )
      {
         return values[ index ];
      }

      void set( int index, Object^ value )
      {
         values[ index ] = value;
      }
   }

   property Object^ Value
   {
      Object^ get()
      {
         return "the value";
      }
   }

   TestClass() 
   {
      Name = "initialName";
      values = gcnew array<Object^> {(int^)0,1,2,3,4,5,6,7,8,9};
      methodCalled = 0;
   }

   TestClass(String^ initName)
   {
      Name = initName;
      values = gcnew array<Object^> {(int^)0,1,2,3,4,5,6,7,8,9};
      methodCalled = 0;
   }

   static void SayHello()
   {
      Console::WriteLine( "Hello" );
   }

   void AddUp()
   {
      methodCalled++;
      Console::WriteLine( "AddUp Called {0} times", methodCalled );
   }

   static double ComputeSum( double d1, double d2 )
   {
      return d1 + d2;
   }

   static void PrintName( String^ firstName, String^ lastName )
   {
      Console::WriteLine( "{0},{1}", lastName, firstName );
   }

   void PrintTime()
   {
      Console::WriteLine( DateTime::Now );
   }

   void Swap( interior_ptr<int> a, interior_ptr<int> b )
   {
      int x =  *a;
       *a =  *b;
       *b = x;
   }
};


[DefaultMemberAttribute("PrintTime")]
public ref class TestClass2
{
public:
   void PrintTime()
   {
      Console::WriteLine( DateTime::Now );
   }

};

public ref class Base
{
private:
    static int BaseOnlyPrivate = 0;
protected:
    static int BaseOnly = 0;
};

public ref class Derived : Base
{
public:
    static int DerivedOnly = 0;
};

public ref class MostDerived : Derived {};

void main()
{
   array<Object^>^ noArguments;

   // BindingFlags::InvokeMethod
   // Call a static method.
   Type^ t = TestClass::typeid;
   Console::WriteLine();
   Console::WriteLine( "Invoking a static method." );
   Console::WriteLine( "-------------------------" );
   t->InvokeMember( "SayHello", BindingFlags::InvokeMethod | BindingFlags::Public | BindingFlags::Static, 
         nullptr, nullptr, noArguments );

   // BindingFlags::InvokeMethod
   // Call an instance method.
   TestClass^ c = gcnew TestClass;
   Console::WriteLine();
   Console::WriteLine( "Invoking an instance method." );
   Console::WriteLine( "----------------------------" );
   c->GetType()->InvokeMember( "AddUp", BindingFlags::InvokeMethod, nullptr, c, noArguments );
   c->GetType()->InvokeMember( "AddUp", BindingFlags::InvokeMethod, nullptr, c, noArguments );

   // BindingFlags::InvokeMethod
   // Call a method with parameters.
   array<Object^>^args = {100.09,184.45};
   Object^ result;
   Console::WriteLine();
   Console::WriteLine( "Invoking a method with parameters." );
   Console::WriteLine( "---------------------------------" );
   result = t->InvokeMember( "ComputeSum", BindingFlags::InvokeMethod, nullptr, nullptr, args );
   Console::WriteLine( " {0} + {1} = {2}", args[ 0 ], args[ 1 ], result );

   // BindingFlags::GetField, SetField
   Console::WriteLine();
   Console::WriteLine( "Invoking a field (getting and setting.)" );
   Console::WriteLine( "--------------------------------------" );

   // Get a field value.
   result = t->InvokeMember( "Name", BindingFlags::GetField, nullptr, c, noArguments );
   Console::WriteLine( "Name == {0}", result );

   // Set a field.
   array<Object^>^obj2 = {"NewName"};
   t->InvokeMember( "Name", BindingFlags::SetField, nullptr, c, obj2 );
   result = t->InvokeMember( "Name", BindingFlags::GetField, nullptr, c, noArguments );
   Console::WriteLine( "Name == {0}", result );
   Console::WriteLine();
   Console::WriteLine( "Invoking an indexed property (getting and setting.)" );
   Console::WriteLine( "--------------------------------------------------" );

   // BindingFlags::GetProperty
   // Get an indexed property value.
   int index = 3;
   array<Object^>^obj3 = {index};
   result = t->InvokeMember( "Item", BindingFlags::GetProperty, nullptr, c, obj3 );
   Console::WriteLine( "Item->Item[ {0}] == {1}", index, result );

   // BindingFlags::SetProperty
   // Set an indexed property value.
   index = 3;
   array<Object^>^obj4 = {index,"NewValue"};
   t->InvokeMember( "Item", BindingFlags::SetProperty, nullptr, c, obj4 );
   result = t->InvokeMember( "Item", BindingFlags::GetProperty, nullptr, c, obj3 );
   Console::WriteLine( "Item->Item[ {0}] == {1}", index, result );
   Console::WriteLine();
   Console::WriteLine( "Getting a field or property." );
   Console::WriteLine( "----------------------------" );

   // BindingFlags::GetField
   // Get a field or property.
   result = t->InvokeMember( "Name", static_cast<BindingFlags>(BindingFlags::GetField | 
       BindingFlags::GetProperty), nullptr, c, noArguments );
   Console::WriteLine( "Name == {0}", result );

   // BindingFlags::GetProperty
   result = t->InvokeMember( "Value", static_cast<BindingFlags>(BindingFlags::GetField | 
       BindingFlags::GetProperty), nullptr, c, noArguments );
   Console::WriteLine( "Value == {0}", result );
   Console::WriteLine();
   Console::WriteLine( "Invoking a method with named parameters." );
   Console::WriteLine( "---------------------------------------" );

   // BindingFlags::InvokeMethod
   // Call a method using named parameters.
   array<Object^>^argValues = {"Mouse","Micky"};
   array<String^>^argNames = {"lastName","firstName"};
   t->InvokeMember( "PrintName", BindingFlags::InvokeMethod, nullptr, nullptr, argValues, nullptr, 
       nullptr, argNames );
   Console::WriteLine();
   Console::WriteLine( "Invoking a default member of a type." );
   Console::WriteLine( "------------------------------------" );

   // BindingFlags::Default
   // Call the default member of a type.
   Type^ t3 = TestClass2::typeid;
   t3->InvokeMember( "", static_cast<BindingFlags>(BindingFlags::InvokeMethod | BindingFlags::Default), 
        nullptr, gcnew TestClass2, noArguments );

   // BindingFlags::Static, NonPublic, and Public
   // Invoking a member with ref parameters.
   Console::WriteLine();
   Console::WriteLine( "Invoking a method with ref parameters." );
   Console::WriteLine( "--------------------------------------" );
   MethodInfo^ m = t->GetMethod( "Swap" );
   args = gcnew array<Object^>(2);
   args[ 0 ] = 1;
   args[ 1 ] = 2;
   m->Invoke( gcnew TestClass, args );
   Console::WriteLine( "{0}, {1}", args[ 0 ], args[ 1 ] );

   // BindingFlags::CreateInstance
   // Creating an instance with a parameterless constructor.
   Console::WriteLine();
   Console::WriteLine( "Creating an instance with a parameterless constructor." );
   Console::WriteLine( "------------------------------------------------------" );
   Object^ obj = t->InvokeMember( "TestClass", static_cast<BindingFlags>(BindingFlags::Public | 
       BindingFlags::Instance | BindingFlags::CreateInstance), nullptr, nullptr, noArguments );
   Console::WriteLine("Instance of {0} created.", obj->GetType()->Name);

   // Creating an instance with a constructor that has parameters.
   Console::WriteLine();
   Console::WriteLine( "Creating an instance with a constructor that has parameters." );
   Console::WriteLine( "------------------------------------------------------------" );
   obj = t->InvokeMember( "TestClass", static_cast<BindingFlags>(BindingFlags::Public | 
       BindingFlags::Instance | BindingFlags::CreateInstance), nullptr, nullptr, 
       gcnew array<Object^> { "Hello, World!" } );
   Console::WriteLine("Instance of {0} created with initial value '{1}'.", obj->GetType()->Name, 
       obj->GetType()->InvokeMember("Name", BindingFlags::GetField, nullptr, obj, noArguments));

   // BindingFlags::DeclaredOnly
   Console::WriteLine();
   Console::WriteLine( "DeclaredOnly instance members." );
   Console::WriteLine( "------------------------------" );
   array<System::Reflection::MemberInfo^>^memInfo = t->GetMembers( BindingFlags::DeclaredOnly | 
       BindingFlags::Instance | BindingFlags::Public);
   for ( int i = 0; i < memInfo->Length; i++ )
   {
      Console::WriteLine( memInfo[ i ]->Name );

   }

   // BindingFlags::IgnoreCase
   Console::WriteLine();
   Console::WriteLine( "Using IgnoreCase and invoking the PrintName method." );
   Console::WriteLine( "---------------------------------------------------" );
   t->InvokeMember( "printname", static_cast<BindingFlags>(BindingFlags::IgnoreCase | 
                BindingFlags::Static | BindingFlags::Public | BindingFlags::InvokeMethod), 
                nullptr, nullptr, gcnew array<Object^> {"Brad","Smith"});

   // BindingFlags::FlattenHierarchy
   Console::WriteLine();
   Console::WriteLine( "Using FlattenHierarchy to get inherited static protected and public members." );
   Console::WriteLine( "----------------------------------------------------------------------------" );
   array<FieldInfo^>^ finfos = MostDerived::typeid->GetFields(BindingFlags::NonPublic | 
         BindingFlags::Public | BindingFlags::Static | BindingFlags::FlattenHierarchy);
   for each (FieldInfo^ finfo in finfos)
   {
       Console::WriteLine("{0} defined in {1}.", finfo->Name, finfo->DeclaringType->Name);
   }

   Console::WriteLine();
   Console::WriteLine("Without FlattenHierarchy." );
   Console::WriteLine("-------------------------");
   finfos = MostDerived::typeid->GetFields(BindingFlags::NonPublic | BindingFlags::Public |
         BindingFlags::Static);
   for each (FieldInfo^ finfo in finfos)
   {
       Console::WriteLine("{0} defined in {1}.", finfo->Name, finfo->DeclaringType->Name);
   }
};

/* This example produces output similar to the following:

Invoking a static method.
-------------------------
Hello

Invoking an instance method.
----------------------------
AddUp Called 1 times
AddUp Called 2 times

Invoking a method with parameters.
---------------------------------
 100.09 + 184.45 = 284.54

Invoking a field (getting and setting.)
--------------------------------------
Name == initialName
Name == NewName

Invoking an indexed property (getting and setting.)
--------------------------------------------------
Item->Item[ 3] == 3
Item->Item[ 3] == NewValue

Getting a field or property.
----------------------------
Name == NewName
Value == the value

Invoking a method with named parameters.
---------------------------------------
Mouse,Micky

Invoking a default member of a type.
------------------------------------
12/23/2009 4:19:06 PM

Invoking a method with ref parameters.
--------------------------------------
2, 1

Creating an instance with a parameterless constructor.
------------------------------------------------------
Instance of TestClass created.

Creating an instance with a constructor that has parameters.
------------------------------------------------------------
Instance of TestClass created with initial value 'Hello, World!'.

DeclaredOnly instance members.
------------------------------
get_Item
set_Item
get_Value
AddUp
PrintTime
Swap
.ctor
.ctor
Value
Item
Name
methodCalled

Using IgnoreCase and invoking the PrintName method.
---------------------------------------------------
Smith,Brad

Using FlattenHierarchy to get inherited static protected and public members.
----------------------------------------------------------------------------
DerivedOnly defined in Derived.
BaseOnly defined in Base.

Without FlattenHierarchy.
-------------------------

 */

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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