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)
| Member name | Description | |
|---|---|---|
![]() | 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. |
![]() ![]() | 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 no binding flag. |
![]() ![]() | 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. 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 coercions, which never lose data. An example of a widening coercion is coercing 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 coercion, which may lose data. An example of a narrowing coercion is coercing a 64-bit signed integer to a 32-bit signed integer. The default binder ignores this flag, while custom binders can implement the semantics of this flag. |
![]() ![]() | 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. |
![]() | GetProperty | Specifies that the value of the specified property should be returned. |
![]() ![]() | 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. |
![]() ![]() | 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. Parameters with default values are used only in calls where trailing arguments are omitted. They must be the last arguments. |
![]() ![]() | 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. |
![]() | 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. |
![]() ![]() | 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 |
Note |
|---|
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 System; using System.Reflection; using System.IO; namespace BindingFlagsSnippet { class Example { static void Main() { // BindingFlags.InvokeMethod // Call a static method. Type t = typeof (TestClass); Console.WriteLine(); Console.WriteLine("Invoking a static method."); Console.WriteLine("-------------------------"); t.InvokeMember ("SayHello", BindingFlags.InvokeMethod | BindingFlags.Public | BindingFlags.Static, null, null, new object [] {}); // BindingFlags.InvokeMethod // Call an instance method. TestClass c = new TestClass (); Console.WriteLine(); Console.WriteLine("Invoking an instance method."); Console.WriteLine("----------------------------"); c.GetType().InvokeMember ("AddUp", BindingFlags.InvokeMethod, null, c, new object [] {}); c.GetType().InvokeMember ("AddUp", BindingFlags.InvokeMethod, null, c, new object [] {}); // BindingFlags.InvokeMethod // Call a method with parameters. object [] args = new object [] {100.09, 184.45}; object result; Console.WriteLine(); Console.WriteLine("Invoking a method with parameters."); Console.WriteLine("---------------------------------"); result = t.InvokeMember ("ComputeSum", BindingFlags.InvokeMethod, null, null, 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, null, c, new object [] {}); Console.WriteLine ("Name == {0}", result); // Set a field. t.InvokeMember ("Name", BindingFlags.SetField, null, c, new object [] {"NewName"}); result = t.InvokeMember ("Name", BindingFlags.GetField, null, c, new object [] {}); 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; result = t.InvokeMember ("Item", BindingFlags.GetProperty, null, c, new object [] {index}); Console.WriteLine ("Item[{0}] == {1}", index, result); // BindingFlags.SetProperty // Set an indexed property value. index = 3; t.InvokeMember ("Item", BindingFlags.SetProperty, null, c, new object [] {index, "NewValue"}); result = t.InvokeMember ("Item", BindingFlags.GetProperty , null, c, new object [] {index}); Console.WriteLine ("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", BindingFlags.GetField | BindingFlags.GetProperty, null, c, new object [] {}); Console.WriteLine ("Name == {0}", result); // BindingFlags.GetProperty result = t.InvokeMember ("Value", BindingFlags.GetField | BindingFlags.GetProperty, null, c, new object [] {}); 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. object[] argValues = new object [] {"Mouse", "Micky"}; String [] argNames = new String [] {"lastName", "firstName"}; t.InvokeMember ("PrintName", BindingFlags.InvokeMethod, null, null, argValues, null, null, 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 = typeof (TestClass2); t3.InvokeMember ("", BindingFlags.InvokeMethod | BindingFlags.Default, null, new TestClass2(), new object [] {}); // 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 = new object[2]; args[0] = 1; args[1] = 2; m.Invoke(new 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 cobj = t.InvokeMember ("TestClass", BindingFlags.Public | BindingFlags.Instance | BindingFlags.CreateInstance, null, null, new object [] {}); Console.WriteLine("Instance of {0} created.", cobj.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("------------------------------------------------------------"); cobj = t.InvokeMember ("TestClass", BindingFlags.Public | BindingFlags.Instance | BindingFlags.CreateInstance, null, null, new object [] { "Hello, World!" }); Console.WriteLine("Instance of {0} created with initial value '{1}'.", cobj.GetType().Name, cobj.GetType().InvokeMember("Name", BindingFlags.GetField, null, cobj, null)); // BindingFlags.DeclaredOnly Console.WriteLine(); Console.WriteLine("DeclaredOnly instance members."); Console.WriteLine("------------------------------"); 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", BindingFlags.IgnoreCase | BindingFlags.Static | BindingFlags.Public | BindingFlags.InvokeMethod, null, null, new object[] {"Brad","Smith"}); // BindingFlags.FlattenHierarchy Console.WriteLine(); Console.WriteLine("Using FlattenHierarchy to get inherited static protected and public members." ); Console.WriteLine("----------------------------------------------------------------------------"); FieldInfo[] finfos = typeof(MostDerived).GetFields(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy); foreach (FieldInfo finfo in finfos) { Console.WriteLine("{0} defined in {1}.", finfo.Name, finfo.DeclaringType.Name); } Console.WriteLine(); Console.WriteLine("Without FlattenHierarchy." ); Console.WriteLine("-------------------------"); finfos = typeof(MostDerived).GetFields(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static); foreach (FieldInfo finfo in finfos) { Console.WriteLine("{0} defined in {1}.", finfo.Name, finfo.DeclaringType.Name); } } } public class TestClass { public String Name; private Object [] values = new Object [] {0, 1,2,3,4,5,6,7,8,9}; public Object this [int index] { get { return values[index]; } set { values[index] = value; } } public Object Value { get { return "the value"; } } public TestClass () : this("initialName") {} public TestClass (string initName) { Name = initName; } int methodCalled = 0; public static void SayHello () { Console.WriteLine ("Hello"); } public void AddUp () { methodCalled++; Console.WriteLine ("AddUp Called {0} times", methodCalled); } public static double ComputeSum (double d1, double d2) { return d1 + d2; } public static void PrintName (String firstName, String lastName) { Console.WriteLine ("{0},{1}", lastName,firstName); } public void PrintTime () { Console.WriteLine (DateTime.Now); } public void Swap(ref int a, ref int b) { int x = a; a = b; b = x; } } [DefaultMemberAttribute ("PrintTime")] public class TestClass2 { public void PrintTime () { Console.WriteLine (DateTime.Now); } } public class Base { static int BaseOnlyPrivate = 0; protected static int BaseOnly = 0; } public class Derived : Base { public static int DerivedOnly = 0; } public class MostDerived : Derived {} } /* 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[3] == 3 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 4:29:21 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 Item Value Name 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. ------------------------- */
Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.


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