ReturnValueNameAttribute Class

.NET Framework 4.6 and 4.5

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

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

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

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

The ReturnValueNameAttribute type exposes the following members.

  NameDescription
Public methodReturnValueNameAttributeInitializes a new instance of the ReturnValueNameAttribute class, and specifies the name of the return value.
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  NameDescription
Public propertyNameGets the name that was specified for the return value of a method in a Windows Runtime component.
Public propertyTypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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  NameDescription
Public methodEqualsInfrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
Public methodGetHashCodeReturns the hash code for this instance. (Inherited from Attribute.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsDefaultAttributeWhen overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
Public methodMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Explicit interface implemetationPrivate method_Attribute.GetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.InvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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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 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)
{
    …
}

.NET Framework

Supported in: 4.6, 4.5

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

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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