Attribute.GetCustomAttribute Method (Assembly, Type, Boolean)


Retrieves a custom attribute 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 Shared Function GetCustomAttribute (
	element As Assembly,
	attributeType As Type,
	inherit As Boolean
) As Attribute


Type: System.Reflection.Assembly

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

Type: System.Type

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

Type: System.Boolean

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

Return Value

Type: System.Attribute

A reference to the single custom attribute of type attributeType that is applied to element, or null if there is no such attribute.

Exception Condition

element or attributeType is null.


attributeType is not derived from Attribute.


More than one of the requested attributes was found.


Starting with the .NET Framework version 2.0, this method returns security attributes if the attributes are 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 the GetCustomAttribute method taking an Assembly as a parameter.

Imports System
Imports System.Reflection
Imports Microsoft.VisualBasic

' Add an AssemblyDescription attribute.
<Assembly: AssemblyDescription("A sample description")> 

Module DemoModule
    Sub Main()
        ' Get the assembly for this module.
        Dim assy As System.Reflection.Assembly = GetType(DemoModule).Assembly
        ' Store the assembly name.
        Dim assyName As String = assy.GetName().Name
        ' See if the AssemblyDescription attribute is defined.
        If Attribute.IsDefined(assy, GetType(AssemblyDescriptionAttribute)) _
            ' Affirm that the attribute is defined. Assume the filename of
            ' this code example is "IsDef1VB".
            Console.WriteLine("The AssemblyDescription attribute is " & _
                "defined for assembly {0}.", assyName)
            ' Get the description attribute itself.
            Dim attr As Attribute = Attribute.GetCustomAttribute( _
                assy, GetType(AssemblyDescriptionAttribute))
            ' Display the description.
            If Not attr Is Nothing And _
                TypeOf attr Is AssemblyDescriptionAttribute Then
                Dim adAttr As AssemblyDescriptionAttribute = _
                    CType(attr, AssemblyDescriptionAttribute)
                Console.WriteLine("The description is " & _
                    Chr(34) & "{0}" & Chr(34) & ".", adAttr.Description)
                Console.WriteLine("The description could not be retrieved.")
            End If
            Console.WriteLine("The AssemblyDescription attribute is not " & _
                              "defined for assembly {0}.", assyName)
        End If
    End Sub
End Module

' Output:
' The AssemblyDescription attribute is defined for assembly IsDef1VB.
' The description is "A sample description".

.NET Framework
Available since 1.1
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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