.NET Framework Class Library
AttributeIsDefined Method (ParameterInfo, Type)

Determines whether any custom attributes are applied to a method parameter. Parameters specify the method parameter, and the type of the custom attribute to search for.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)
Syntax
Public Shared Function IsDefined ( _
	element As [%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_0_0_0%], _
	attributeType As [%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_0_0_1%] _
) As [%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_0_0_2%]
public static [%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_1_0_0%] IsDefined(
	[%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_1_0_1%] element,
	[%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_1_0_2%] attributeType
)
public:
static [%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_2_0_0%] IsDefined(
	[%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_2_0_1%]^ element, 
	[%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_2_0_2%]^ attributeType
)
static member IsDefined : 
        element:[%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_3_0_0%] * 
        attributeType:[%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_3_0_1%] -> [%$TOPIC/kw9ayb6s_en-us_VS_110_1_0_3_0_2%]

Parameters

element
Type: System.ReflectionParameterInfo

An object derived from the ParameterInfo class that describes a parameter of a member of a class.

attributeType
Type: SystemType

The type, or a base type, of the custom attribute to search for.

Return Value

Type: SystemBoolean
true if a custom attribute of type attributeType is applied to element; otherwise, false.
Exceptions
ExceptionCondition
ArgumentNullException

element or attributeType is .

ArgumentException

attributeType is not derived from Attribute.

Remarks

The ancestors of element are searched for custom attributes.

Examples

The following code example illustrates the use of IsDefined, taking a ParameterInfo as a parameter.

Imports System
Imports System.Reflection

Module DemoModule
    Public Class TestClass
        ' Assign a ParamArray attribute to the parameter using the keyword. 
        Public Sub Method1(ByVal ParamArray args As String())
        End Sub 
    End Class 

    Sub Main()
        ' Get the class type to access its metadata. 
        Dim clsType As Type = GetType(TestClass)
        ' Get the MethodInfo object for Method1. 
        Dim mInfo As MethodInfo = clsType.GetMethod("Method1")
        ' Get the ParameterInfo array for the method parameters. 
        Dim pInfo() As ParameterInfo = mInfo.GetParameters()
        If Not pInfo(0) Is Nothing Then 
            ' See if the ParamArray attribute is defined. 
            Dim isDef As Boolean = Attribute.IsDefined(pInfo(0), _
                                   GetType(ParamArrayAttribute))
            Dim strDef As String 
            If isDef = True Then
                strDef = "is" 
            Else
                strDef = "is not" 
            End If 
            ' Display the result.
            Console.WriteLine("The ParamArray attribute {0} defined " & _
                              "for parameter {1} of method {2}.", _
                              strDef, pInfo(0).Name, mInfo.Name)
        Else
            Console.WriteLine("Could not retrieve parameter information " & _
                              "for method {0}.", mInfo.Name)
        End If 
    End Sub 
End Module 

' Output: 
' The ParamArray attribute is defined for parameter args of method Method1.
using System;
using System.Reflection;

namespace IsDef5CS 
{
    public class TestClass 
    {
        // Assign a ParamArray attribute to the parameter using the keyword. 
        public void Method1(params String[] args)
        {}
    }

    public class DemoClass 
    {
        static void Main(string[] args) 
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);
            // Get the MethodInfo object for Method1.
            MethodInfo mInfo = clsType.GetMethod("Method1");
            // Get the ParameterInfo array for the method parameters.
            ParameterInfo[] pInfo = mInfo.GetParameters();
            if (pInfo != null) 
            {
                // See if the ParamArray attribute is defined. 
                bool isDef = Attribute.IsDefined(pInfo[0], 
                                                 typeof(ParamArrayAttribute));
                // Display the result.
                Console.WriteLine("The ParamArray attribute {0} defined for " +
                                  "parameter {1} of method {2}.",
                                  isDef ? "is" : "is not",
                                  pInfo[0].Name, 
                                  mInfo.Name);
            }
            else
                Console.WriteLine("The parameters information could " +
                            "not be retrieved for method {0}.", mInfo.Name);
        }
    }
}

/*
 * Output:
 * The ParamArray attribute is defined for parameter args of method Method1.
 */
using namespace System;
using namespace System::Reflection;

namespace IsDef5CS
{
   public ref class TestClass
   {
   public:

      // Assign a ParamArray attribute to the parameter using the keyword. 
      void Method1(... array<String^>^args ){}

   };

   ref class DemoClass
   {
   public:
      static void Main()
      {

         // Get the class type to access its metadata.
         Type^ clsType = TestClass::typeid;

         // Get the MethodInfo object for Method1.
         MethodInfo^ mInfo = clsType->GetMethod( "Method1" );

         // Get the ParameterInfo array for the method parameters. 
         array<ParameterInfo^>^pInfo = mInfo->GetParameters();
         if ( pInfo != nullptr )
         {

            // See if the ParamArray attribute is defined. 
            bool isDef = Attribute::IsDefined( pInfo[ 0 ], ParamArrayAttribute::typeid );

            // Display the result.
            Console::WriteLine( "The ParamArray attribute {0} defined for " 
            "parameter {1} of method {2}.", isDef ? (String^)"is" : "is not", pInfo[ 0 ]->Name, mInfo->Name );
         }
         else
                  Console::WriteLine( "The parameters information could " 
         "not be retrieved for method {0}.", mInfo->Name );
      }

   };

}

/*
 * Output:
 * The ParamArray attribute is defined for parameter args of method Method1.
 */
Version Information

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8
Platforms

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, 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.