Attribute.GetCustomAttributes Method (ParameterInfo) (System)

Imports System
Imports System.Reflection
Imports System.ComponentModel

Module DemoModule
    Public Class AClass
        ' Add Description and ParamArray (with the keyword) attributes.
        Public Sub ParamArrayAndDesc( _
            <Description("This argument is a ParamArray")> _
            ByVal ParamArray args() As Integer)
        End Sub
    End Class

    Sub Main()
        ' Get the Class type to access its metadata.
        Dim clsType As Type = GetType(AClass)
        ' Get the type information for the method.
        Dim mInfo As MethodInfo = clsType.GetMethod("ParamArrayAndDesc")
        ' Get the Parameter information for the method.
        Dim pInfo() As ParameterInfo = mInfo.GetParameters()
        Dim attr As Attribute
        ' Iterate through each attribute of the parameter.
        For Each attr In Attribute.GetCustomAttributes(pInfo(0))
            ' Check for the ParamArray attribute.
            If TypeOf attr Is ParamArrayAttribute Then
                ' Convert the attribute to access its data.
                Dim paAttr As ParamArrayAttribute = _
                    CType(attr, ParamArrayAttribute)
                Console.WriteLine("Parameter {0} has the " + _
                    "ParamArray attribute.", pInfo(0).Name)
            ' Check for the Description attribute.
            ElseIf TypeOf attr Is DescriptionAttribute Then
                ' Convert the attribute to access its data.
                Dim descAttr As DescriptionAttribute = _
                    CType(attr, DescriptionAttribute)
                Console.WriteLine("Parameter {0} has a description " + _
                    "attribute. The description is:", pInfo(0).Name)
                Console.WriteLine(descAttr.Description)
            End If
        Next
    End Sub
End Module

' Output:
' Parameter args has a description attribute. The description is:
' This argument is a ParamArray
' Parameter args has the ParamArray attribute.

using System;
using System.Reflection;
using System.ComponentModel;

namespace CustAttrs5CS {
    public class AClass {
        public void ParamArrayAndDesc(
            // Add ParamArray (with the keyword) and Description attributes.
            [Description("This argument is a ParamArray")]
            params int[] args)
        {}
    }

    class DemoClass {
        static void Main(string[] args) {
            // Get the Class type to access its metadata.
            Type clsType = typeof(AClass);
            // Get the type information for the method.
            MethodInfo mInfo = clsType.GetMethod("ParamArrayAndDesc");
            if (mInfo != null) {
                // Get the parameter information.
                ParameterInfo[] pInfo = mInfo.GetParameters();
                if (pInfo != null) {
                    // Iterate through all the attributes for the parameter.
                    foreach(Attribute attr in 
                        Attribute.GetCustomAttributes(pInfo[0])) {
                        // Check for the ParamArray attribute.
                        if (attr.GetType() == typeof(ParamArrayAttribute))
                            Console.WriteLine("Parameter {0} for method {1} " +
                                "has the ParamArray attribute.",
                                pInfo[0].Name, mInfo.Name);
                        // Check for the Description attribute.
                        else if (attr.GetType() == 
                            typeof(DescriptionAttribute)) {
                            Console.WriteLine("Parameter {0} for method {1} " +
                                "has a description attribute.",
                                pInfo[0].Name, mInfo.Name);
                            Console.WriteLine("The description is: \"{0}\"",
                                ((DescriptionAttribute)attr).Description);
                        }
                    }
                }
            }
        }
    }
}

/*
 * Output:
 * Parameter args for method ParamArrayAndDesc has a description attribute.
 * The description is: "This argument is a ParamArray"
 * Parameter args for method ParamArrayAndDesc has the ParamArray attribute.
 */

using namespace System;
using namespace System::Reflection;
using namespace System::ComponentModel;

namespace CustAttrs5CS
{
   public ref class AClass
   {
   public:
      void ParamArrayAndDesc(
         // Add ParamArray and Description attributes.
         [Description("This argument is a ParamArray")]
         array<Int32>^args )
      {}
   };

   ref class DemoClass
   {
   public:
      static void Main()
      {
         // Get the Class type to access its metadata.
         Type^ clsType = AClass::typeid;

         // Get the type information for the method.
         MethodInfo^ mInfo = clsType->GetMethod( "ParamArrayAndDesc" );
         if ( mInfo != nullptr )
         {
            // Get the parameter information.
            array<ParameterInfo^>^pInfo = mInfo->GetParameters();
            if ( pInfo != nullptr )
            {
               // Iterate through all the attributes for the parameter.
               System::Collections::IEnumerator^ myEnum4 = Attribute::GetCustomAttributes( pInfo[ 0 ] )->GetEnumerator();
               while ( myEnum4->MoveNext() )
               {
                  Attribute^ attr = safe_cast<Attribute^>(myEnum4->Current);

                  // Check for the ParamArray attribute.
                  if ( attr->GetType() == ParamArrayAttribute::typeid )
                                    Console::WriteLine( "Parameter {0} for method {1} "
                  "has the ParamArray attribute.", pInfo[ 0 ]->Name, mInfo->Name );
                  // Check for the Description attribute.
                  else

                  // Check for the Description attribute.
                  if ( attr->GetType() == DescriptionAttribute::typeid )
                  {
                     Console::WriteLine( "Parameter {0} for method {1} "
                     "has a description attribute.", pInfo[ 0 ]->Name, mInfo->Name );
                     Console::WriteLine( "The description is: \"{0}\"", (dynamic_cast<DescriptionAttribute^>(attr))->Description );
                  }
               }
            }
         }
      }
   };
}

/*
 * Output:
 * Parameter args for method ParamArrayAndDesc has a description attribute.
 * The description is: "This argument is a ParamArray"
 * Parameter args for method ParamArrayAndDesc has the ParamArray attribute.
 */