ValueTypeIndexerReference<TOperand, TItem> Class

.NET Framework (current version)

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Represents an element referenced by an indexer on a value type that can be used as an l-value in an expression.

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

          System.Activities.Expressions.ValueTypeIndexerReference<TOperand, TItem>

public sealed class ValueTypeIndexerReference<TOperand, TItem> : CodeActivity<Location<TItem>>

Type Parameters


The value type with the indexer.


The type of indexer array.

System_CAPS_pubmethodValueTypeIndexerReference<TOperand, TItem>()

Initializes a new instance of the ValueTypeIndexerReference<TOperand, TItem> class.


Gets the identifier of the cache that is unique within the scope of the workflow definition.(Inherited from Activity.)


Gets or sets an optional friendly name that is used for debugging, validation, exception handling, and tracking.(Inherited from Activity.)


Gets an identifier that is unique in the scope of the workflow definition.(Inherited from Activity.)


Gets or sets the implementation version of the activity.(Inherited from CodeActivity<TResult>.)


Gets a collection of arguments that represent the indices of the element in the indexer array.


Gets or sets the instance of the value type that contains the indexer.


Gets or sets the result argument for the Activity<TResult>.(Inherited from Activity<TResult>.)


When implemented in a derived class, gets the type of an activity OutArgument.(Inherited from ActivityWithResult.)


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Serves as the default hash function. (Inherited from Object.)


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


Indicates whether the DisplayName property should be serialized.(Inherited from Activity.)


Returns a String that contains the Id and DisplayName of the Activity.(Inherited from Activity.)

The following code example uses ValueTypeIndexerReference<TOperand, TItem> in an Assign activity to assign a string value to the struct element at index 1 and prints the element value to the console. The Assign activity is equivalent to the following statement when using the struct defined in the following example: myStructVariable[1] = "Hello";.


Instead of instantiating the ValueTypeIndexerReference<TOperand, TItem> l-value expression activity directly, it is strongly recommended that you call ConvertReference<TResult>, which provides a higher level of abstraction and enables you to implement your workflow more intuitively.

    // Define a struct with an indexer.
    struct StructWithIndexer
        string val;
        public string this[int index]
            get { return val; }
            set { val = value; }

    public static void ValueTypeIndexerReferenceSample()
        // Create a variable of type StructWithIndexer to store the element.
        var swivar = new Variable<StructWithIndexer>("swivar", new StructWithIndexer());

        // Create the top-level activity to be invoked later.
        Activity myActivity = new Sequence
            Variables = { swivar },
            Activities = 
                // Create an Assign activity with an element at index 1.
                new Assign<string>
                    To = new ValueTypeIndexerReference<StructWithIndexer, string>
                        OperandLocation = swivar,
                        Indices = { new InArgument<int>(1) },
                    // Assign a string literal to the element at index 1.
                    Value = "Hello",
                new WriteLine()
                    Text = ExpressionServices.Convert<string>(ctx => swivar.Get(ctx)[1]),

        // Invoke the Sequence activity.

.NET Framework
Available since 4.0

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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