Windows apps
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ReturnValueNameAttribute Class

.NET Framework (current version)
 

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)

System.Object
  System.Attribute
    System.Runtime.InteropServices.WindowsRuntime.ReturnValueNameAttribute

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

NameDescription
System_CAPS_pubmethodReturnValueNameAttribute(String)

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

NameDescription
System_CAPS_pubpropertyName

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

System_CAPS_pubpropertyTypeId

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

NameDescription
System_CAPS_pubmethodEquals(Object)

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.)

System_CAPS_pubmethodGetHashCode()

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

System_CAPS_pubmethodGetType()

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

System_CAPS_pubmethodIsDefaultAttribute()

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

System_CAPS_pubmethodMatch(Object)

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

System_CAPS_pubmethodToString()

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

NameDescription
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.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfoCount(UInt32)

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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