ObsoleteAttribute Class


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Marks the program elements that are no longer in use. This class cannot be inherited.

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


[AttributeUsageAttribute(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Enum | AttributeTargets.Constructor | AttributeTargets.Method | AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Event | AttributeTargets.Interface | AttributeTargets.Delegate, 
	Inherited = false)]
public sealed class ObsoleteAttribute : Attribute


Initializes a new instance of the ObsoleteAttribute class with default properties.


Initializes a new instance of the ObsoleteAttribute class with a specified workaround message.

System_CAPS_pubmethodObsoleteAttribute(String, Boolean)

Initializes a new instance of the ObsoleteAttribute class with a workaround message and a Boolean value indicating whether the obsolete element usage is considered an error.


Gets a Boolean value indicating whether the compiler will treat usage of the obsolete program element as an error.


Gets the workaround message, including a description of the alternative program elements.


When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)


This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.)


Returns the hash code for this instance.(Inherited from Attribute.)


Gets the Type of the current instance.(Inherited from Object.)


When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)


When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)


Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)


Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

ObsoleteAttribute is applicable to all program elements except assemblies, modules, parameters, and return values. Marking an element as obsolete informs users that the element will be removed in future versions of the product.

The ObsoleteAttribute class includes two properties:

  • Message. The string assigned to the Message property is emitted by the compiler when the attribute target is used in code. The string should note that the attribute target is obsolete and, if possible, provide some workaround or programmatic alternative.

  • IsError. This is a Boolean value that indicates to the compiler whether using the ObsoleteAttribute attribute should cause it to emit an error (IsError is true) or a warning (IsError is false).

For more information about using attributes, see Extending Metadata Using Attributes.

When you create a Windows Metadata library (.winmd file), the ObsoleteAttribute is exported as both the ObsoleteAttribute attribute and the Windows.Foundation.Metadata.DeprecatedAttribute attribute if only the ObsoleteAttribute is present in source code. The ObsoleteAttribute is transformed to the DeprecatedAttribute as follows:

  • If the message and error arguments are both present, message is assigned to the DeprecatedAttributemessage argument. An error value of true maps to DeprecationType.Remove, and an error value of false maps to DeprecationType.Deprecate.

  • If the message argument is not supplied in the ObsoleteAttribute, its default value in the DeprecatedAttribute is "element_name is deprecated", where element_name is the name of the target program element to which the attribute is applied.

  • If the error argument is not present in the ObsoleteAttribute, its default value in the DeprecatedAttribute is DeprecationType.Deprecate.


Directly applying the Windows.Foundation.Metadata.DeprecatedAttribute attribute to managed code is not recommended, because this export occurs automatically.

The following example defines a class that contains a property and a method that are marked with the ObsoleteAttribute attribute. Accessing the value of the OldProperty property in code generates a compiler warning, but calling the CallOldMethod method generates a compiler error. The example also shows the output that results when you attempt to compile the source code.

using System;
using System.Reflection;

public class Example
   // Mark OldProperty As Obsolete.
   [ObsoleteAttribute("This property is obsolete. Use NewProperty instead.", false)] 
   public static string OldProperty
   { get { return "The old property value."; } }

   public static string NewProperty
   { get { return "The new property value."; } }

   // Mark CallOldMethod As Obsolete.
   [ObsoleteAttribute("This method is obsolete. Call CallNewMethod instead.", true)] 
   public static string CallOldMethod()
      return "You have called CallOldMethod.";

   public static string CallNewMethod() 
      return "You have called CallNewMethod.";

   public static void Main()
// The attempt to compile this example produces output like the following output:
//    Example.cs(31,25): error CS0619: 'Example.CallOldMethod()' is obsolete: 
//            'This method is obsolete. Call CallNewMethod instead.'
//    Example.cs(29,25): warning CS0618: 'Example.OldProperty' is obsolete: 
//            'This property is obsolete. Use NewProperty instead.'

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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