LambdaValue<TResult> Class

.NET Framework (current version)

Represents a lambda expression used as an r-value, which supports binding of In arguments.

Namespace: System.Activities.Expressions
Assembly: System.Activities (in System.Activities.dll)

Inheritance Hierarchy

System::Object
System.Activities::Activity
System.Activities::ActivityWithResult
System.Activities::Activity<TResult>
System.Activities::CodeActivity<TResult>
System.Activities.Expressions::LambdaValue<TResult>

Syntax

C++

generic<typename TResult>
public ref class LambdaValue sealed : CodeActivity<TResult>, 
	IValueSerializableExpression

Type Parameters

TResult: The type of value returned by the expression.

Constructors

	Name	Description
	LambdaValue<TResult>(Expression<Func<ActivityContext^, TResult>^>^)	Initializes a new instance of the LambdaValue<TResult> class using the specified expression.

Properties

	Name	Description
	CacheId	Gets the identifier of the cache that is unique within the scope of the workflow definition.(Inherited from Activity.)
	DisplayName	Gets or sets an optional friendly name that is used for debugging, validation, exception handling, and tracking.(Inherited from Activity.)
	Id	Gets an identifier that is unique in the scope of the workflow definition.(Inherited from Activity.)
	ImplementationVersion	Gets or sets the implementation version of the activity.(Inherited from CodeActivity<TResult>.)
	Result	Gets or sets the result argument for the Activity<TResult>.(Inherited from Activity<TResult>.)
	ResultType	When implemented in a derived class, gets the type of an activity OutArgument.(Inherited from ActivityWithResult.)

Methods

	Name	Description
	CanConvertToString(IValueSerializerContext^)	This method always returns true and is used in conjunction with ConvertToString to provide descriptive error messages when an attempt is made to serialize this activity to XAML.
	ConvertToString(IValueSerializerContext^)	Throws a LambdaSerializationException, and is used in conjunction with CanConvertToString to provide descriptive error messages when an attempt is made to serialize this activity to XAML.
	Equals(Object^)	Determines whether the specified object is equal to the current object.(Inherited from Object.)
	GetHashCode()	Serves as the default hash function. (Inherited from Object.)
	GetType()	Gets the Type of the current instance.(Inherited from Object.)
	ShouldSerializeDisplayName()	Indicates whether the DisplayName property should be serialized.(Inherited from Activity.)
	ToString()	Returns a String that contains the Id and DisplayName of the Activity.(Inherited from Activity.)

LambdaValue<TResult> is used for lambda expressions specified in code and cannot be serialized to XAML. If an attempt to serialize a workflow that contains a LambdaValue<TResult> is made, a LambdaSerializationException is thrown. If the containing workflow requires XAML serialization, use VisualBasicValue<TResult> or use ExpressionServices to convert the LambdaValue<TResult> to a format that can be serialized.

This activity uses the LINQ to Entity provider to evaluate LINQ expressions. Any LINQ expressions used with this activity must be evaluatable by the ADO.Net Entity Data Model. For example, LINQ expressions cannot be used to reference activities, variables, or arguments of the workflow itself.

Version Information

.NET Framework
Available since 4.0

Thread Safety

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