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ReturnValueNameAttribute Class

.NET Framework (current version)

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Specifies the name of the return value of a method in a Windows Runtime component.

Namespace:   System.Runtime.InteropServices.WindowsRuntime
Assembly:  mscorlib (in mscorlib.dll)


[AttributeUsageAttribute(AttributeTargets.Delegate | AttributeTargets.ReturnValue, 
	AllowMultiple = false, Inherited = false)]
public sealed class ReturnValueNameAttribute : Attribute


Initializes a new instance of the ReturnValueNameAttribute class, and specifies the name of the return value.


Gets the name that was specified for the return value of a method in a Windows Runtime component.


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.)

In a Windows Runtime component, all the parameters of a method and the return value must have names. By default, Winmdexp.exe (Windows Runtime Metadata Export Tool) gives the return value the name "value". When you use a component in a Windows 8.x Store app written in JavaScript, you can use this name to retrieve the return value. For example, suppose a component defines a method that has a return value and two out parameters (ByRef parameters with the OutAttribute attribute in Visual Basic):

public static int ComputeAverage([ReadOnlyArray()] int[] input,
    out int minValue, out int maxValue)

When you call the function from JavaScript, you can access the return value by its default name (value):

var data = [5, 13, 23, 37];
var results = SampleComponent.TestStuff.computeAverage(data);
var formattedResults = "Min=" + results.minValue + ", Avg=" + 
    results.value + ", Max=" + results.maxValue;

You must give the return value a different name if you already have a parameter named "value". Or you might simply want to use a more meaningful name (such as "average" in this example). Apply the ReturnValueNameAttribute attribute to your method and specify a new name.

[return: ReturnValueName("average")]
public static int ComputeAverage([ReadOnlyArray()] int[] input,
    out int minValue, out int maxValue)

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.5
Portable Class Library
Supported in: portable .NET platforms
Windows Phone Silverlight
Available since 8.0
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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