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IsDefined Method (MemberInfo, Type)

Attribute.IsDefined Method (MemberInfo, Type)

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

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

public static bool IsDefined(
	MemberInfo element,
	Type attributeType
)

Parameters

element
Type: System.Reflection.MemberInfo

An object derived from the MemberInfo class that describes a constructor, event, field, method, type, or property member of a class.

attributeType
Type: System.Type

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

Return Value

Type: System.Boolean
true if a custom attribute of type attributeType is applied to element; otherwise, false.

ExceptionCondition
ArgumentNullException

element or attributeType is null.

ArgumentException

attributeType is not derived from Attribute.

NotSupportedException

element is not a constructor, method, property, event, type, or field.

The ancestors of element are searched for custom attributes.

NoteNote

Starting with the .NET Framework version 2.0, this method returns true if a type, method, or constructor has security attributes stored in the new metadata format. Assemblies compiled with version 2.0 or later use the new format. Dynamic assemblies and assemblies compiled with earlier versions of the .NET Framework use the old XML format. See Emitting Declarative Security Attributes.

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

using System;
using System.Reflection;

namespace IsDef4CS 
{
    public class TestClass 
    {
        // Assign the Obsolete attribute to a method.
        [Obsolete("This method is obsolete. Use Method2 instead.")]
        public void Method1()
        {}
        public void Method2()
        {}
    }

    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");
            // See if the Obsolete attribute is defined for this method. 
            bool isDef = Attribute.IsDefined(mInfo, typeof(ObsoleteAttribute));
            // Display the result.
            Console.WriteLine("The Obsolete Attribute {0} defined for {1} of class {2}.",
                isDef ? "is" : "is not", mInfo.Name, clsType.Name);
            // If it's defined, display the attribute's message. 
            if (isDef) 
            {
                ObsoleteAttribute obsAttr = 
                                 (ObsoleteAttribute)Attribute.GetCustomAttribute( 
                                                    mInfo, typeof(ObsoleteAttribute));
                if (obsAttr != null)
                    Console.WriteLine("The message is: \"{0}\".",
                        obsAttr.Message);
                else
                    Console.WriteLine("The message could not be retrieved.");
            }
        }
    }
}

/*
 * Output:
 * The Obsolete Attribute is defined for Method1 of class TestClass.
 * The message is: "This method is obsolete. Use Method2 instead.".
 */

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

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

Portable Class Library

Supported in: Portable Class Library
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