Attribute.IsDefined Method (ParameterInfo, Type, Boolean)

 

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

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

Public Shared Function IsDefined (
	element As ParameterInfo,
	attributeType As Type,
	inherit As Boolean
) As Boolean

Parameters

element
Type: System.Reflection.ParameterInfo

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

true 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.

ExecutionEngineException

element is not a method, constructor, or type.

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.

.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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