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Attribute::GetCustomAttribute Method (MemberInfo^, Type^, Boolean)

.NET Framework (current version)
 

Retrieves a custom attribute 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.

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

C#
C++
F#
VB
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public:
static Attribute^ GetCustomAttribute(
	MemberInfo^ element,
	Type^ attributeType,
	bool inherit
)

Parameters

element
Type: System.Reflection::MemberInfo^

An object derived from the MemberInfo class that describes a constructor, event, field, method, 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::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
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.

AmbiguousMatchException

More than one of the requested attributes was found.

TypeLoadException

A custom attribute type cannot be loaded.

System_CAPS_noteNote

Starting with the .NET Framework version 2.0, this method returns security attributes on types, methods, and constructors 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 a MemberInfo as a parameter.

C#
C++
VB
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using namespace System;
using namespace System::Reflection;

namespace IsDef4CS
{
   public ref class TestClass
   {
   public:

      // Assign the Obsolete attribute to a method.

      [Obsolete("This method is obsolete. Use Method2 instead.")]
      void Method1(){}

      void Method2(){}

   };

   ref class DemoClass
   {
   public:
      static void Main()
      {

         // Get the class type to access its metadata.
         Type^ clsType = TestClass::typeid;

         // Get the MethodInfo object for Method1.
         MethodInfo^ mInfo = clsType->GetMethod( "Method1" );

         // See if the Obsolete attribute is defined for this method.
         bool isDef = Attribute::IsDefined( mInfo, ObsoleteAttribute::typeid );

         // Display the result.
         Console::WriteLine( "The Obsolete Attribute {0} defined for {1} of class {2}.", isDef ? (String^)"is" : "is not", mInfo->Name, clsType->Name );

         // If it's defined, display the attribute's message.
         if ( isDef )
         {
            ObsoleteAttribute^ obsAttr = dynamic_cast<ObsoleteAttribute^>(Attribute::GetCustomAttribute( mInfo, ObsoleteAttribute::typeid ));
            if ( obsAttr != nullptr )
                        Console::WriteLine( "The message is: \"{0}\".", obsAttr->Message );
            else
                        Console::WriteLine( "The message could not be retrieved." );
         }
      }

   };

}


/*
 * Output:
 * The Obsolete Attribute is defined for Method1 of class TestClass.
 * The message is: "This method is obsolete. Use Method2 instead.".
 */

.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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