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Attribute.IsDefined Method (Assembly, Type, Boolean)

Determines whether any custom attributes are applied to an assembly. Parameters specify the assembly, the type of the custom attribute to search for, and an ignored search option.

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

public static bool IsDefined (
	Assembly element,
	Type attributeType,
	bool inherit
)
public static boolean IsDefined (
	Assembly element, 
	Type attributeType, 
	boolean inherit
)
public static function IsDefined (
	element : Assembly, 
	attributeType : Type, 
	inherit : boolean
) : boolean
Not applicable.

Parameters

element

An object derived from the Assembly class that describes a reusable collection of modules.

attributeType

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

inherit

This parameter is ignored, and does not affect the operation of this method.

Return Value

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

Exception typeCondition

ArgumentNullException

element or attributeType is a null reference (Nothing in Visual Basic).

ArgumentException

attributeType is not derived from Attribute.

NoteNote:

Starting with the .NET Framework version 2.0, this method returns true if the assembly 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 an Assembly as a parameter.

using System;
using System.Reflection;

// Add an AssemblyDescription attribute
[assembly: AssemblyDescription("A sample description")]
namespace IsDef1CS
{
    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(DemoClass);
            // Get the assembly object.
            Assembly assy = clsType.Assembly;
            // Store the assembly's name.
            String assyName = assy.GetName().Name;
            // See if the Assembly Description is defined.
            bool isdef = Attribute.IsDefined(assy, 
                typeof(AssemblyDescriptionAttribute));
            if (isdef)
            {
                // Affirm that the attribute is defined.
                Console.WriteLine("The AssemblyDescription attribute " +
                    "is defined for assembly {0}.", assyName);
                // Get the description attribute itself.
                AssemblyDescriptionAttribute adAttr = 
                    (AssemblyDescriptionAttribute)Attribute.GetCustomAttribute(
                    assy, typeof(AssemblyDescriptionAttribute));
                // Display the description.
                if (adAttr != null)
                    Console.WriteLine("The description is \"{0}\".", 
                        adAttr.Description);
                else
                    Console.WriteLine("The description could not " +
                        "be retrieved.");            
            }
            else
                Console.WriteLine("The AssemblyDescription attribute is not " +
                    "defined for assembly {0}.", assyName);
        }
    }
}

/*
 * Output:
 * The AssemblyDescription attribute is defined for assembly IsDef1CS.
 * The description is "A sample description".
 */

package IsDef1JSL; 
import System.*;
import System.Reflection.*;

// Add an AssemblyDescription attribute
/** @assembly AssemblyDescription("A sample description")
 */
class DemoClass
{
    public static void main(String[] args)
    {
        // Get the class type to access its metadata.
        Type clsType = DemoClass.class.ToType();
        // Get the assembly object.
        Assembly assy = clsType.get_Assembly();
        // Store the assembly's name.
        String assyName = assy.GetName().get_Name();
        //Type assyType = assy.GetType();
        // See if the Assembly Description is defined.
        boolean isdef = Attribute.IsDefined(assy, 
            AssemblyDescriptionAttribute.class.ToType());
        if (isdef) {
            // Affirm that the attribute is defined.
            Console.WriteLine("The AssemblyDescription attribute " 
                + "is defined for assembly {0}.", assyName);
            // Get the description attribute itself.
            AssemblyDescriptionAttribute adAttr = (AssemblyDescriptionAttribute)
                (Attribute.GetCustomAttribute(assy, 
                AssemblyDescriptionAttribute.class.ToType()));
            // Display the description.
            if (adAttr != null) {
                Console.WriteLine("The description is \"{0}\".", 
                    adAttr.get_Description());
            }
            else {
                Console.WriteLine("The description could not " 
                    + "be retrieved.");
            }
        }
        else {
            Console.WriteLine("The AssemblyDescription attribute is not " 
                + "defined for assembly {0}.", assyName);
        }
    } //main
} //DemoClass

/*
   Output:
   The AssemblyDescription attributeis defined for assembly IsDef1JSL.
   The description is "A sample description".
*/

import System;
import System.Reflection;

// Add an AssemblyDescription attribute
[assembly: AssemblyDescription("A sample description")]

package IsDef1JS
{
    class DemoClass
    {
        static function Main() : void 
        {
            // Get the class type to access its metadata.
            var clsType : Type = DemoClass;
            // Get the assembly object.
            var assy : Assembly = clsType.Assembly;
            // Store the assembly's name.
            var assyName : String = assy.GetName().Name;
            //Type assyType = assy.GetType();
            // See if the Assembly Description is defined.
            var isdef : boolean = Attribute.IsDefined(assy, AssemblyDescriptionAttribute);
            if (isdef)
            {
                // Affirm that the attribute is defined.
                Console.WriteLine("The AssemblyDescription attribute " +
	                "is defined for assembly {0}.", assyName);
                // Get the description attribute itself.
                var adAttr : AssemblyDescriptionAttribute = 
	                AssemblyDescriptionAttribute(Attribute.GetCustomAttribute(
	                assy, AssemblyDescriptionAttribute));
                // Display the description.
                if (adAttr != null)
	                Console.WriteLine("The description is \"{0}\".", 
		                adAttr.Description);
                else
	                Console.WriteLine("The description could not " +
		                "be retrieved.");			
            }
            else
                Console.WriteLine("The AssemblyDescription attribute is not " +
	                "defined for assembly {0}.", assyName);
        }
    }
}

IsDef1JS.DemoClass.Main();

/*
 * Output:
 * The AssemblyDescription attributeis defined for assembly IsDef1CS.
 * The description is "A sample description".
 */

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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