ParameterInfo.IsDefined(Type, Boolean) Method

Definition

Namespace:

System.Reflection

Assembly:

System.Runtime.dll

Source:

ParameterInfo.cs

Determines whether the custom attribute of the specified type or its derived types is applied to this parameter.

public:
 virtual bool IsDefined(Type ^ attributeType, bool inherit);

public virtual bool IsDefined (Type attributeType, bool inherit);

abstract member IsDefined : Type * bool -> bool
override this.IsDefined : Type * bool -> bool

Public Overridable Function IsDefined (attributeType As Type, inherit As Boolean) As Boolean

Parameters

attributeType

Type

The Type object to search for.

inherit

Boolean

This argument is ignored for objects of this type.

Returns

Boolean

true if one or more instances of attributeType or its derived types are applied to this parameter; otherwise, false.

Implements

IsDefined(Type, Boolean)

Exceptions

ArgumentNullException

attributeType is null.

ArgumentException

attributeType is not a Type object supplied by the common language runtime.

Examples

The following example defines two custom attributes, MyAttribute and MyDerivedAttribute. MyDerivedAttribute is derived from MyAttribute. The example then applies these attributes to the parameters of a method of an example class.

When the example is run, it uses the IsDefined method to test all parameters of all methods in the example class. It then displays the parameters that have MyAttribute or MyDerivedAttribute.

// System::Reflection::ParameterInfo::GetCustomAttributes(Type, bool)
// System::Reflection::ParameterInfo::IsDefined(Type, bool)
using namespace System;
using namespace System::Reflection;

// Define a custom attribute with one named parameter.
[AttributeUsage(AttributeTargets::Parameter)]
public ref class MyAttribute: public Attribute
{
private:
   String^ myName;

public:
   MyAttribute( String^ name )
   {
      myName = name;
   }

   property String^ Name 
   {
      String^ get()
      {
         return myName;
      }
   }
};

// Derive another custom attribute from MyAttribute.
[AttributeUsage(AttributeTargets::Parameter)]
public ref class MyDerivedAttribute: public MyAttribute
{
public:
   MyDerivedAttribute( String^ name ) : MyAttribute( name ) {}
};

// Define a class with a method that has three parameters. Apply
// MyAttribute to one parameter, MyDerivedAttribute to another, and
// no attributes to the third. 
public ref class MyClass1
{
public:
   void MyMethod( [MyAttribute("This is an example parameter attribute")] 
                  int i,
                  [MyDerivedAttribute("This is another parameter attribute")] 
                  int j,
                  int k ){}
};

void main()
{
   // Get the type of the class 'MyClass1'.
   Type^ myType = MyClass1::typeid;

   // Get the members associated with the class 'MyClass1'.
   array<MethodInfo^>^myMethods = myType->GetMethods();

   // For each method of the class 'MyClass1', display all the parameters
   // to which MyAttribute or its derived types have been applied.
   for each ( MethodInfo^ mi in myMethods )
   {
      // Get the parameters for the method.
      array<ParameterInfo^>^ myParameters = mi->GetParameters();
      if ( myParameters->Length > 0 )
      {
         Console::WriteLine("\nThe following parameters of {0} have MyAttribute or a derived type:", mi);
         for each ( ParameterInfo^ pi in myParameters)
         {
            if (pi->IsDefined(MyAttribute::typeid, false))
            {
               Console::WriteLine("Parameter {0}, name = {1}, type = {2}", 
                  pi->Position, pi->Name, pi->ParameterType);
            }
         }
      }
   }
}

/* This code example produces the following output:

The following parameters of Void MyMethod(Int32, Int32, Int32) have MyAttribute or a derived type:
Parameter 0, name = i, type = System.Int32
Parameter 1, name = j, type = System.Int32

The following parameters of Boolean Equals(System.Object) have MyAttribute or a derived type:
 */

using System;
using System.Reflection;

// Define a custom attribute with one named parameter.
[AttributeUsage(AttributeTargets.Parameter)]
public class MyAttribute : Attribute
{
    private string myName;
    public MyAttribute(string name)
    {
        myName = name;
    }
    public string Name
    {
        get
        {
            return myName;
        }
    }
}

// Derive another custom attribute from MyAttribute
[AttributeUsage(AttributeTargets.Parameter)]
public class MyDerivedAttribute : MyAttribute
{
    public MyDerivedAttribute(string name) : base(name) {}
}

// Define a class with a method that has three parameters. Apply
// MyAttribute to one parameter, MyDerivedAttribute to another, and
// no attributes to the third.
public class MyClass1
{
    public void MyMethod(
        [MyAttribute("This is an example parameter attribute")]
        int i,
        [MyDerivedAttribute("This is another parameter attribute")]
        int j,
        int k )
    {
        return;
    }
}

public class MemberInfo_GetCustomAttributes
{
    public static void Main()
    {
        // Get the type of the class 'MyClass1'.
        Type myType = typeof(MyClass1);
        // Get the members associated with the class 'MyClass1'.
        MethodInfo[] myMethods = myType.GetMethods();

        // For each method of the class 'MyClass1', display all the parameters
        // to which MyAttribute or its derived types have been applied.
        foreach (MethodInfo mi in myMethods)
        {
            // Get the parameters for the method.
            ParameterInfo[] myParameters = mi.GetParameters();
            if (myParameters.Length > 0)
            {
                Console.WriteLine("\nThe following parameters of {0} have MyAttribute or a derived type: ", mi);
                foreach (ParameterInfo pi in myParameters)
                {
                    if (pi.IsDefined(typeof(MyAttribute), false))
                    {
                        Console.WriteLine("Parameter {0}, name = {1}, type = {2}",
                            pi.Position, pi.Name, pi.ParameterType);
                    }
                }
            }
        }
    }
}

/* This code example produces the following output:

The following parameters of Void MyMethod(Int32, Int32, Int32) have MyAttribute or a derived type:
Parameter 0, name = i, type = System.Int32
Parameter 1, name = j, type = System.Int32

The following parameters of Boolean Equals(System.Object) have MyAttribute or a derived type:
 */

Imports System.Reflection

' Define a custom attribute with one named parameter.
<AttributeUsage(AttributeTargets.Parameter)> _
Public Class MyAttribute
    Inherits Attribute
    Private myName As String

    Public Sub New(ByVal name As String)
        myName = name
    End Sub 

    Public ReadOnly Property Name() As String
        Get
            Return myName
        End Get
    End Property
End Class 

' Derive another custom attribute from MyAttribute
<AttributeUsage(AttributeTargets.Parameter)> _
Public Class MyDerivedAttribute
    Inherits MyAttribute

    Public Sub New(ByVal name As String)
        MyBase.New(name)
    End Sub 
End Class

' Define a class with a method that has three parameters. Apply
' MyAttribute to one parameter, MyDerivedAttribute to another, and
' no attributes to the third. 
Public Class MyClass1

    Public Sub MyMethod(<MyAttribute("This is an example parameter attribute")> _
                        ByVal i As Integer, _
                        <MyDerivedAttribute("This is another parameter attribute")> _
                        ByVal j As Integer, _
                        ByVal k As Integer)
        Return
    End Sub 
End Class 

Public Class MemberInfo_GetCustomAttributes

    Public Shared Sub Main()
        ' Get the type of the class 'MyClass1'.
        Dim myType As Type = GetType(MyClass1)
        ' Get the members associated with the class 'MyClass1'.
        Dim myMethods As MethodInfo() = myType.GetMethods()

        ' For each method of the class 'MyClass1', display all the parameters
        ' to which MyAttribute or its derived types have been applied.
        For Each mi As MethodInfo In myMethods
            ' Get the parameters for the method.
            Dim myParameters As ParameterInfo() = mi.GetParameters()
            If myParameters.Length > 0 Then
                Console.WriteLine(vbCrLf & "The following parameters of {0} have MyAttribute or a derived type: ", mi)
                For Each pi As ParameterInfo In myParameters
                    If pi.IsDefined(GetType(MyAttribute), False) Then
                        Console.WriteLine("Parameter {0}, name = {1}, type = {2}", _
                            pi.Position, pi.Name, pi.ParameterType)
                    End If
                Next
            End If
        Next
    End Sub 
End Class 

' This code example produces the following output:
'
'The following parameters of Void MyMethod(Int32, Int32, Int32) have MyAttribute or a derived type:
'Parameter 0, name = i, type = System.Int32
'Parameter 1, name = j, type = System.Int32
'
'The following parameters of Boolean Equals(System.Object) have MyAttribute or a derived type:

Remarks

This method ignores the inherit parameter. To search the inheritance chain for attributes on parameters, use the appropriate overloads of the Attribute.IsDefined method.