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IndexerReference<TOperand, TItem> Class

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

System::Object
  System.Activities::Activity
    System.Activities::ActivityWithResult
      System.Activities::Activity<Location<TItem>>
        System.Activities::CodeActivity<Location<TItem>>
          System.Activities.Expressions::IndexerReference<TOperand, TItem>

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

[ContentPropertyAttribute(L"Indices")]
generic<typename TOperand, typename TItem>
public ref class IndexerReference sealed : public CodeActivity<Location<TItem>^>

Type Parameters

TOperand

The type with the indexer.

TItem

The type of the indexer array.

The IndexerReference<TOperand, TItem> type exposes the following members.

  NameDescription
Public methodIndexerReference<TOperand, TItem>Initializes a new instance of the IndexerReference<TOperand, TItem> class.
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  NameDescription
Protected propertyCacheIdGets the identifier of the cache that is unique within the scope of the workflow definition. (Inherited from Activity.)
Protected propertyConstraintsGets a collection of Constraint activities that can be configured to provide validation for the Activity. (Inherited from Activity.)
Public propertyDisplayNameGets or sets an optional friendly name that is used for debugging, validation, exception handling, and tracking. (Inherited from Activity.)
Public propertyIdGets an identifier that is unique in the scope of the workflow definition. (Inherited from Activity.)
Protected propertyImplementationNot supported. (Inherited from CodeActivity<TResult>.)
Public propertyIndicesGets a collection of arguments that represent the indices of the element in the indexer array.
Public propertyOperandGets or sets the object that contains the indexer.
Public propertyResultGets or sets the result argument for the Activity<TResult>. (Inherited from Activity<TResult>.)
Public propertyResultTypeWhen implemented in a derived class, gets the type of an activity OutArgument. (Inherited from ActivityWithResult.)
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  NameDescription
Protected methodCacheMetadata(ActivityMetadata)Not implemented. Use CacheMetadata(CodeActivityMetadata) instead. (Inherited from CodeActivity<TResult>.)
Protected methodCacheMetadata(CodeActivityMetadata)Creates and validates a description of the activity’s arguments, variables, child activities, and activity delegates. (Inherited from CodeActivity<TResult>.)
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodExecuteWhen implemented in a derived class, performs the execution of the activity. (Inherited from CodeActivity<TResult>.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodShouldSerializeDisplayNameIndicates whether the DisplayName property should be serialized. (Inherited from Activity.)
Public methodToStringReturns a String that contains the Id and DisplayName of the Activity. (Inherited from Activity.)
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The following code example uses IndexerReference<TOperand, TItem> in an Assign activity to assign an integer value to the object item at index [1,2] and prints the item value to the console. The Assign activity is equivalent to the following statement when using an object that implements an indexer. myObj[1,2] = 4; .

NoteNote

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


    // Define a class with a multi-dimensional indexer.
    public class ObjectWithIndexer
    {
        private int[,] array = new int[10,10];
        public int this[int i, int j]
        {
            get { return array[i,j]; }
            set { array[i,j] = value; }
        }
    }

    public static void IndexerReferenceSample()
    {
        // Create a variable of type ObjectWithIndexer to store the object item.
        var oivar = new Variable<ObjectWithIndexer>("oivar", new ObjectWithIndexer());

        Activity myActivity = new Sequence
        {
            Variables = { oivar },
            Activities = 
            {                    
                // Create an Assign activity with a reference for the object at index [1,2].
                new Assign<int>
                {
                    To = new IndexerReference<ObjectWithIndexer, int>
                    {
                        Operand = oivar,
                        Indices =
                        {
                            new InArgument<int>(1),
                            new InArgument<int>(2)
                        }
                    },
                    // Assign an integer value to the object at index [1,2].
                    Value = 4,
                },
                // Print the new item value to the console.
                new WriteLine()
                {
                    Text = ExpressionServices.Convert<string>(ctx => oivar.Get(ctx)[1, 2].ToString()),
                }
            }
        };

        // Invoke the Sequence activity.
        WorkflowInvoker.Invoke(myActivity);
    }

.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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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