Class ReturnValueAttribute

Binds a parameter of a method interception or method boundary advice to the return value of the target method.

Inheritance

object

Attribute

AdviceParameterAttribute

ReturnValueAttribute

Namespace: PostSharp.Aspects.Advices

Assembly: PostSharp.dll

Syntax

Full screen

public sealed class ReturnValueAttribute : AdviceParameterAttribute

Remarks

The type of the parameter must be the type of the return value, or a type parameter of the advice method. In an async method that a method boundary advice applies to as a state machine, and in a non-async method that returns a task, the return value is the result of the task. An advice can have only one parameter bound by this attribute.

The meaning of the parameter depends on the advice:

In an OnMethodInvokeAdvice, the parameter must be out or ref, and the value that the advice assigns to it is the value returned by the target method. An advice applied to a method that returns a value must have either a parameter bound by this attribute or a MethodInterceptionArgs parameter. When the method returns void, the parameter receives the default value of its type, and the value that the advice assigns to it is ignored.
In an OnMethodSuccessAdvice or an OnMethodExitAdvice, the advice reads the value that the method returns, by value or in, or replaces it with ref. When the method throws, the exit advice reads the default value.
In an OnMethodEntryAdvice or an OnMethodExceptionAdvice, the parameter must be out or ref. It sets the value that the method returns when the advice sets the flow behavior to Return.

In a method boundary advice, an out or ref parameter takes precedence over ReturnValue when the advice has both.

Constructors

Name	Description
ReturnValueAttribute()

Properties

Name Description

Name	Description
IsRequired	Gets or sets a value indicating whether the target method must have a return value. When this property is `true`, the compiler reports an error when the method of a method boundary advice returns `void`, returns a task without a result, returns by reference (`ref` or `ref readonly`), or is an iterator, and when the method of an OnMethodInvokeAdvice returns `void`. When it is `false`, the parameter receives the default value of its type in these methods, and a value that the advice writes to an `out` or `ref` parameter is ignored. The default value is `false`.

IsRequired

Gets or sets a value indicating whether the target method must have a return value. When this property is true, the compiler reports an error when the method of a method boundary advice returns void, returns a task without a result, returns by reference (ref or ref readonly), or is an iterator, and when the method of an OnMethodInvokeAdvice returns void. When it is false, the parameter receives the default value of its type in these methods, and a value that the advice writes to an out or ref parameter is ignored. The default value is false.