Attribute.IsDefined Method (MemberInfo, Type, Boolean)
Determines whether any custom attributes are applied to a member of a type. Parameters specify the member, the type of the custom attribute to search for, and whether to search ancestors of the member.
Assembly: mscorlib (in mscorlib.dll)
Public Shared Function IsDefined ( element As MemberInfo, attributeType As Type, inherit As Boolean ) As Boolean
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.
- inherit
-
Type:
System.Boolean
If true, specifies to also search the ancestors of element for custom attributes.
Return Value
Type: System.Booleantrue if a custom attribute of type attributeType is applied to element; otherwise, false.
| Exception | Condition |
|---|---|
| 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. |
Note |
|---|
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.
Imports System Imports System.Reflection Module DemoModule Public Class TestClass ' Assign the Obsolete attribute to a method. <Obsolete("This method is obsolete. Use Method2() instead.")> _ Public Sub Method1() End Sub Public Sub Method2() 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") ' See if the Obsolete attribute is defined for this method. Dim isDef As Boolean = Attribute.IsDefined(mInfo, _ GetType(ObsoleteAttribute)) Dim strDef As String If isDef = True Then strDef = "is" Else strDef = "is not" End If ' Display the results. Console.WriteLine("The Obsolete attribute {0} defined for " & _ "method {1} of class {2}.", strDef, mInfo.Name, clsType.Name) ' If it's defined, display the attribute's message. If isDef = True Then Dim attr As Attribute = Attribute.GetCustomAttribute(mInfo, _ GetType(ObsoleteAttribute)) If Not attr Is Nothing And TypeOf attr Is ObsoleteAttribute Then Dim obsAttr As ObsoleteAttribute = _ CType(attr, ObsoleteAttribute) Console.WriteLine("The message is: ""{0}""", obsAttr.Message) Else Console.WriteLine("The message could not be retrieved.") End If End If End Sub End Module ' Output: ' The Obsolete attribute is defined for method Method1 of class TestClass. ' The message is: "This method is obsolete. Use Method2() instead."
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
